T cells are a type of white blood cell or lymphocyte that recognizes and targets pathogen-infected cells or cancer cells for clearance. T cells originate from hematopoietic stem cells in the bone marrow, and precursors are shuttled to the thymus for final maturation. T cells are selective, so that they are tolerant to the body’s own cells (self-molecules) but remain highly sensitive to non-self pathogens. There are many subsets of T cells, each with important functions relating to the immune system. T cell populations are highly diverse, comprising multiple T cell subsets with distinct markers, functions, and tissue localization. Immunophenotyping offers a way to identify and quantify the different populations of T cells within a sample, using antibodies to detect specific antigens expressed by these cells, which are known as markers.

Three subtypes that are commonly studied in T cell research include:

Killer T cells  recognize antigens released by the infecting agent that become bound to the host cell. They are capable of identifying and interacting with diverse cell types and pathogens. The T cell receptor binds the foreign antigen, triggering the release of cytotoxins into the infected cell, leading to cell death. CD8 T cells, a major T cell subset, are primarily responsible for cytotoxic responses against tumor cells and infected cells, playing a crucial role in antitumor and infectious immunity.

Helper T cells facilitate the immune system in fighting infection. The cells recognize and bind to a pathogenic antigen, leading to the release of soluble factors (cytokines) that signal to the rest of the immune system to launch a response. The cells are classified into different subsets, including Th1 cells and Th2 cells. Th1 cells bind to phagocytic macrophages and dendritic cells. Th2 cells bind and activate B cells, required for antibody production and, thus, securing lifelong immunity against certain bacterial or viral infections. Helper T cell subsets also include Th9 and Th17 cells, each playing distinct roles in immune responses, autoimmune and inflammatory diseases, and defense against extracellular pathogens. Follicular helper T cells are another specialized subset that supports B cell development and antibody production within germinal centers. Helper T cells (cells helper) support B cells in producing antibodies (cells produce antibodies).

Regulatory T cells keep the immune system in check. They ensure that it is shut down once an immune response has occurred. This regulatory mechanism represses immune activity, thus preventing an exaggerated immune response. Normally functioning Treg cells are critical for safeguarding against autoimmune disease. Regulatory T cells are essential for maintaining immune homeostasis and preventing autoimmune diseases by suppressing excessive immune responses.

Naive T cells, including naïve helper T cells, are mature lymphocytes recently exiting the thymus that circulate through lymphoid organs searching for antigens. They express unique T cell receptors (TCRs) that recognize specific peptide antigens presented by professional antigen-presenting cells (APCs) like dendritic cells, macrophages, and B cells.

Upon antigen recognition via MHC class II on APCs, naïve T cells activate through TCR engagement and co-stimulatory signals, leading to proliferation and differentiation into effector cells such as helper T cells, cytotoxic T cells, and memory cells. Cytokines like interleukin 12 from APCs promote Th1 polarization, shaping adaptive immune responses.

Effector cells execute specialized functions, including cytokine production and immune regulation, with helper T cells orchestrating immune responses against infections. Naive T cells also generate memory cells that provide durable immunity for rapid response upon re-exposure, ensuring effective adaptive immunity.

CD3

CD3 is a core component of the T cell receptor complex and is widely used to identify T cells, including naïve subsets. It is expressed on all mature T cells and plays a role in signal transduction during antigen recognition. In immunophenotyping, CD3 is often combined with markers like CD62L and CD197 to distinguish naïve T cells from memory and effector populations, supporting studies in immunology, vaccine response, and immune monitoring.

Figure 1. Western blot - Anti-CD3 antibody [UCH-T1] (ab215267)

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CD62L

CD62L, also known as L-selectin, is a surface adhesion molecule commonly used to identify naïve T cells. It plays a role in guiding these cells to lymph nodes by mediating their entry through high endothelial venules. Along with other markers like CD3 and CD197, CD62L helps distinguish naïve T cells from memory and effector subsets. Its expression is frequently analyzed in immunophenotyping to study immune surveillance, development, and response to antigens.

Figure 2. Flow Cytometry - Anti-CD62L antibody [EPR23565-109] (ab245239)

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CD197

CD197, also known as CCR7, is a chemokine receptor commonly used to identify naïve T cells. It helps guide these cells to lymphoid tissues by responding to chemokine signals, supporting immune surveillance and homeostasis. Its expression is frequently analyzed in immunology research to explore T cell migration, immune responses, and the development of adaptive immunity.

Figure 3. Flow Cytometry - Anti-CCR7 antibody [4B12] (ab52602)

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Killer CD8 T cells, also known as cytotoxic T lymphocytes, are a key component of the adaptive immune system. They recognize and eliminate infected or abnormal cells through antigen-specific responses. Identifying these cells involves a combination of surface and intracellular markers.

CD8 is the primary surface marker used to define this T cell subset. It is often co-expressed with CD3, confirming T cell lineage. Additional markers such as granzyme B, perforin, and IFN-γ are used to assess cytotoxic function. CD45RA and CD27 can help distinguish between naïve, memory, and effector CD8 T cell populations.

These markers are widely used in flow cytometry and immunophenotyping to study immune responses in infections, cancer, and immunotherapy. Understanding CD8 T cell profiles supports research into immune surveillance, vaccine development, and disease progression.

CD8

CD8 is a surface glycoprotein commonly used to identify cytotoxic T lymphocytes, also known as killer CD8 T cells. These cells play a role in targeting and eliminating infected or abnormal cells. CD8 binds to MHC class I molecules, supporting antigen recognition and T cell activation. In immunophenotyping, CD8 is often used alongside markers like CD3 to study T cell subsets, immune responses, and disease progression in infections, cancer, and immunotherapy research.

Figure 4. Immunohistochemistry (Frozen sections) - Anti-CD8 alpha antibody [EPR21769] (ab217344)

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IFNγ

Interferon gamma (IFNγ) is a cytokine commonly used to assess the functional activity of killer CD8 T cells. It is produced upon antigen recognition and plays a role in enhancing immune responses against infected or malignant cells. IFNγ expression is often measured in flow cytometry or ELISpot assays to evaluate cytotoxic T cell activation. Its presence helps researchers study immune responses in infections, cancer, and immunotherapy applications.

Figure 5. Flow Cytometry (Intracellular) - Anti-Interferon gamma antibody [EPR23991-53] (ab267369)

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TNFα

Tumor necrosis factor alpha (TNFα) is a cytokine produced by activated killer CD8 T cells. It contributes to immune defense by promoting inflammation and supporting the elimination of infected or abnormal cells. TNFα is often measured alongside IFNγ and granzyme B to assess cytotoxic T cell activity. Its expression is commonly analyzed in immunology studies focused on infections, cancer, and immunotherapy, helping researchers evaluate the functional state of CD8 T cells.

Figure 6. Western blot - Anti-TNF alpha antibody [EPR22598-212] (ab255275)

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EOMES

EOMES, or eomesodermin, also known asT-box brain protein 2 (Tbr2), is a transcription factor involved in the development and function of killer CD8 T cells. It supports the expression of cytotoxic molecules like perforin and granzyme B, contributing to the cell’s ability to eliminate infected or malignant targets. EOMES is often combined with T-bet to define effector and memory CD8 T cell subsets. Its expression helps researchers explore T cell differentiation, immune memory, and responses to immunotherapy.

Figure 7. Immunohistochemistry (Formalin/PFA-fixed paraffin-embedded sections) - Anti-TBR2 / Eomes antibody [EPR26474-17] (ab315794).

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Helper CD4 T cells are a central part of the adaptive immune response. They support other immune cells by releasing cytokines and coordinating responses to pathogens. Identifying these cells involves a combination of surface and intracellular markers.

CD4 is the primary marker used to define this T cell subset. It is typically co-expressed with CD3, confirming T cell lineage. Additional markers such as CD45RA and CD45RO help distinguish between naïve and memory CD4 T cells. Functional subsets like Th1, Th2, Th17, and Treg can be further identified using CXCR3, CCR4, CCR6, and FOXP3 markers.

These markers are widely used in flow cytometry and immunophenotyping to study immune regulation, inflammation, and disease progression. Understanding CD4 T cell profiles supports infection, autoimmunity, and immunotherapy research.

CD4

CD4 is a surface glycoprotein widely used to identify helper T cells. It binds to MHC class II molecules and supports antigen recognition, helping activate immune responses. CD4 is typically co-expressed with CD3 and is used to distinguish helper T cells from cytotoxic CD8 T cells. Researchers use CD4 in immunophenotyping to study immune regulation, infection, and autoimmune conditions. Its expression is a key feature in understanding T cell function and immune system dynamics.

Figure 8. Immunohistochemistry (Formalin/PFA-fixed paraffin-embedded sections) - Anti-CD4 antibody [SP35] (ab213215).

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CD183

CD183, also known as CXCR3, is a chemokine receptor commonly used to identify Th1-type helper CD4 T cells. It plays a role in directing T cell migration to inflamed tissues by responding to specific chemokine signals. CD183 is often analyzed alongside CD4 and other markers to distinguish functional T cell subsets. Its expression helps researchers study immune responses in infections, autoimmune conditions, and inflammation-related diseases.

Figure 9. Flow Cytometry - Anti-CXCR3 antibody [EPR23845-44] (ab259865).

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IFNγ

Interferon gamma (IFNγ) is a cytokine produced by Th1-type helper CD4 T cells. It supports immune responses by activating macrophages and enhancing antigen presentation. IFNγ is often used as a functional marker to identify Th1 cells in immunophenotyping studies. Its expression helps researchers explore immune responses in infections, autoimmune diseases, and vaccine development. Measuring IFNγ provides insight into the activity and polarization of CD4 T cell subsets in various immunological contexts.

Figure 10. Immunohistochemistry (Formalin/PFA-fixed paraffin-embedded sections) - Anti-Interferon gamma antibody [EPR21704] (ab231036).

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IL-2

Interleukin-2 (IL-2) is a cytokine produced by activated helper CD4 T cells. It supports T cell proliferation, survival, and differentiation, making it a key marker of T cell activation. IL-2 is often measured in immunological assays to assess CD4 T cell responses during infection, vaccination, or immune regulation studies. Its expression helps researchers evaluate immune dynamics and the functional state of T cells in both healthy and disease-related conditions.

Figure 11. Immunocytochemistry/ Immunofluorescence - Anti-IL-2 antibody [EPR2780] (ab92381).

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IL-4

Interleukin-4 (IL-4) is a cytokine produced by Th2-type helper CD4 T cells. It supports B cell activation, antibody class switching, and the development of humoral immunity. IL-4 is commonly used as a functional marker to identify Th2 cells in immunological studies. Its expression helps researchers explore immune responses in allergy, parasitic infections, and vaccine development. Measuring IL-4 provides insight into the polarization and activity of CD4 T cell subsets in various immune environments.

Figure 12. Flow Cytometry (Intracellular) - Anti-IL-4 antibody [EPR22879-236] (ab225638).

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IL-12

Interleukin-12 (IL-12) is a cytokine produced by antigen-presenting cells that influences the differentiation of naïve CD4 T cells into Th1 cells. It promotes the production of IFNγ and supports cell-mediated immunity. While not produced by CD4 T cells themselves, IL-12 is a key signal in shaping their functional identity. Researchers often study IL-12 in the context of infection, inflammation, and vaccine responses to understand how it guides helper T cell polarization.

Figure 13. Immunohistochemistry (Formalin/PFA-fixed paraffin-embedded sections) - Anti-IL-12A antibody [EP5737] (ab131039).

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IL-18

Interleukin-18 (IL-18) is a pro-inflammatory cytokine that influences helper CD4 T cell activity, particularly in promoting Th1 responses. It works synergistically with IL-12 to enhance IFNγ production, supporting cell-mediated immunity. While IL-18 is not produced by CD4 T cells, its signaling shapes their functional differentiation. Researchers often study IL-18 in the context of infection, inflammation, and autoimmune conditions to understand how it modulates CD4 T cell responses and contributes to immune regulation.

Figure 14. Immunohistochemistry (Formalin/PFA-fixed paraffin-embedded sections) - Anti-IL-18 antibody [EPR19954-188] (ab243091).

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Signal transducer and activator of transcription 1 (STAT1)

Signal Transducer and Activator of Transcription 1 (STAT1) is a transcription factor involved in cytokine signaling pathways that influence helper CD4 T cell differentiation. It is particularly active in Th1 lineage development, where it supports T-bet expression and IFNγ production. STAT1 activity helps shape immune responses by modulating gene expression in response to signals like IFNγ and IL-6. Its role in defining T cell function makes it a useful marker for studying immune regulation, inflammation, and host defense mechanisms.

Figure 15. Immunohistochemistry (Formalin/PFA-fixed paraffin-embedded sections) - Anti-STAT1 antibody [EPR21057-141] - ChIP Grade (ab234400).

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Signal transducer and activator of transcription 4 (STAT4)

Signal Transducer and Activator of Transcription 4 (STAT4) is a crucial transcription factor predominantly expressed in helper CD4 T cells. It plays a vital role in mediating the effects of interleukin 12 (IL-12) signaling, driving the differentiation of naïve helper T cells into Th1 effector cells. STAT4 activation promotes the production of interferon-gamma (IFN-γ), enhancing cell-mediated immune responses. Due to its specific expression and function, STAT4 serves as an important marker for identifying and studying helper CD4 T cell subsets involved in adaptive immunity.

Figure 16. Immunohistochemistry (Formalin/PFA-fixed paraffin-embedded sections) - Anti-STAT4 antibody [EPR25128-48] (ab284408).

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CD194

CD194, also known as CCR4, is a chemokine receptor commonly expressed on subsets of helper CD4 T cells. It plays a role in guiding these cells to specific tissue sites, particularly during immune responses. Researchers often use CD194 to identify and study Th2 and regulatory T cell populations. Its expression pattern helps distinguish functional subsets, offering insights into immune regulation and potential therapeutic strategies in immunology, oncology, and infectious disease research.

Figure 17. Western blot - Anti-CCR4 antibody [EPR26522-156] (ab315446).

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Th1 T cells are a subset of CD4+ helper T cells that support immune responses against intracellular pathogens. A combination of surface and intracellular markers typically identifies these cells. CD3 and CD4 confirm T cell identity and helper lineage, while CD28 provides costimulatory signals for activation. CD45, a pan-leukocyte marker, helps distinguish naive and memory T cells. Th1 cells are known for producing cytokines like interferon gamma (IFNγ) and tumor necrosis factor alpha (TNFα), which promote inflammation and macrophage activation. The transcription factor T-bet plays a central role in Th1 differentiation by regulating IFNγ expression and guiding lineage commitment. Together, these markers help researchers characterize Th1 cells in various contexts, including infection, autoimmunity, and cancer. Understanding their expression patterns supports the development of targeted therapies and enhances insights into immune system dynamics.

CD3

CD3 is a core component of the T cell receptor complex and is expressed on all mature T cells, including Th1 cells. It plays a key role in signal transduction during antigen recognition. While not exclusive to Th1 cells, CD3 is used alongside markers like CD4, T-bet, and IFNγ to identify this subset. Its consistent expression makes it a reliable starting point for profiling Th1 responses in infection, inflammation, and immunotherapy research

Figure 18. Multiplex immunohistochemistry - Anti-CD3 epsilon antibody [SP7] (ab16669).

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CD4

CD4 is a surface glycoprotein expressed on helper T cells, including Th1 cells. It plays a role in stabilizing interactions between the T cell receptor and MHC class II molecules. In Th1 cells, CD4 is used alongside markers like T-bet, IFNγ, and CD3 to define this subset. While CD4 is not exclusive to Th1 cells, its presence is a key step in identifying helper T cell populations in studies of immune responses, inflammation, and disease progression.

Figure 19. Flow Cytometry - Anti-CD4 antibody [EPR7276] (ab133622).

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CD28

CD28 is a co-stimulatory receptor expressed on T cells, including Th1 subsets. It enhances T cell activation by binding to ligands CD80 or CD86 on antigen-presenting cells. In Th1 cells, CD28 signaling supports cytokine production, including IFNγ and TNFα, and promotes survival and proliferation. While not exclusive to Th1 cells, CD28 is commonly used alongside markers like CD3, CD4, and T-bet to identify and study Th1 responses in immune profiling and disease research

Figure 20. Immunocytochemistry/ Immunofluorescence - Anti-CD28 antibody [EPR24592-5] (ab283860).

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CD45

CD45 is a transmembrane protein tyrosine phosphatase expressed on all nucleated hematopoietic cells, including Th1 T cells. It regulates T cell receptor signaling and is used to distinguish immune cell subsets. In Th1 profiling, CD45 is often combined with markers like CD3, CD4, and T-bet to identify activated or memory T cells. Its expression patterns help researchers study immune responses in inflammation, infection, and cancer, supporting the development of targeted immunotherapies.

Figure 21. Immunocytochemistry/ Immunofluorescence - Anti-CD45 antibody [EPR27167-58] (ab303670).

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IFNγ

Interferon gamma (IFNγ) is a signature cytokine produced by Th1 T cells during immune responses. It plays a role in activating macrophages, enhancing antigen presentation, and promoting inflammation. IFNγ is widely used as a functional marker to identify Th1 cells in both research and clinical settings.

Figure 22. Western blot - Anti-Interferon gamma antibody (ab9657).

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TNFα

Tumor necrosis factor alpha (TNFα) is a proinflammatory cytokine produced by activated Th1 T cells. It contributes to immune responses by promoting inflammation, enhancing antigen presentation, and supporting macrophage activation. TNFα is often used alongside IFNγ and T-bet to identify Th1 cells in immunological studies. Its expression helps researchers investigate immune dynamics in infection, autoimmunity, and cancer, offering insights into T cell function and the inflammatory environment of disease models

Figure 23. Immunocytochemistry/ Immunofluorescence - Anti-TNF alpha antibody [EPR19147] (ab183218).

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T-bet

T-bet is a transcription factor that guides the differentiation of CD4+ T cells into the Th1 lineage. It promotes the expression of interferon gamma (IFNγ) and supports the Th1 cytokine profile. T-bet also influences the expression of chemokine receptors that direct Th1 cell migration. Used alongside markers like CD3, CD4, and IFNγ, T-bet helps researchers identify Th1 cells and study their role in immune responses to infection, inflammation, and autoimmune conditions.

Figure 24. Immunohistochemistry (Formalin/PFA-fixed paraffin-embedded sections) - Anti-T-bet / Tbx21 antibody [EPR27094-16] (ab307193).

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Th2 T cells are a subset of CD4+ helper T cells involved in humoral immunity and allergic responses. These cells are typically identified using a combination of surface and intracellular markers. CD3 and CD4 confirm T cell identity and helper lineage, while CD45 helps distinguish between naive and memory populations. CD184 (CXCR4) and CD365 (TIM-1) are surface markers associated with Th2 migration and activation. GATA3 is a transcription factor that drives Th2 differentiation and supports the expression of cytokines like interleukin-4 (IL-4), a key functional marker of Th2 activity.

These markers help researchers characterize Th2 responses in allergy, asthma, and parasitic infections. Scientists can better understand Th2 cell behavior and their role in immune regulation and disease progression by combining surface and intracellular markers.

CD3

CD3 is a core component of the T cell receptor complex and is expressed on all mature T cells, including Th2 cells. It plays a role in transmitting activation signals during antigen recognition. While CD3 is not specific to Th2 cells, it is used alongside markers like CD4, GATA3, and IL-4 to identify this subset. CD3 helps researchers define total T cell populations before further profiling Th2 responses in allergy, infection, and immune regulation.

Figure 25. Immunohistochemistry (Formalin/PFA-fixed paraffin-embedded sections) - Anti-CD3 antibody [SP162] (ab135372).

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CD184

CD184, also known as CXCR4, is a chemokine receptor expressed on Th2 T cells. It binds to CXCL12 and supports cell migration to specific tissue sites. In Th2 cells, CD184 works alongside markers like CD3, CD4, and GATA3 to define this subset. Its expression is associated with immune responses in allergy and inflammation. Researchers use CD184 to study Th2 cell trafficking, tissue localization, and their role in shaping the immune environment.

Figure 26. Immunohistochemistry (Formalin/PFA-fixed paraffin-embedded sections) - Anti-CXCR4 antibody [UMB2] (ab124824).

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CD365

CD365, also known as TIM-1, is a surface protein expressed on activated Th2 T cells. It enhances T cell activation and cytokine production, particularly interleukin-4 (IL-4). CD365 is often used alongside markers like CD3, CD4, and GATA3 to identify Th2 cells in allergy and inflammation studies. Its expression supports research into immune regulation, tissue tolerance, and the development of targeted therapies for Th2-driven conditions.

Figure 27. Immunocytochemistry/ Immunofluorescence - Anti-TIM 1 antibody [EPR22650-136] (ab228973).

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GATA3

GATA3 is a transcription factor that plays a defining role in developing Th2 T cells. It regulates the expression of Th2-associated cytokines such as IL-4, IL-5, and IL-13. GATA3 is commonly used alongside markers like CD3, CD4, and CD365 to identify Th2 cells in allergy and inflammation studies. Its expression helps researchers explore Th2-driven immune responses and understand how T cell lineages contribute to disease and immune regulation.

Figure 28. Immunohistochemistry (Formalin/PFA-fixed paraffin-embedded sections) - Anti-GATA3 antibody [EPR16651] - ChIP Grade (ab199428).

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IL-4

Interleukin-4 (IL-4) is a signature cytokine produced by Th2 T cells and plays a role in shaping humoral immunity. It promotes B cell class switching to IgE and supports the differentiation of naive CD4+ T cells into the Th2 lineage. IL-4 is commonly used alongside markers like CD3, CD4, and GATA3 to identify Th2 cells.

Figure 29. Western blot - Anti-IL-4 antibody (ab9622).

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Th17 T cells are a subset of CD4+ helper T cells involved in mucosal defense and inflammatory responses. These cells are identified using a combination of surface and intracellular markers. CD3 and CD4 confirm T cell identity and helper lineage, while CD194 (CCR4) is associated with Th17 cell migration. IL-17A is a signature cytokine produced by Th17 cells and is commonly used to assess their activity. The differentiation of Th17 cells is influenced by cytokines such as transforming growth factor beta (TGFβ) and interleukin-6 (IL-6), which guide lineage commitment and cytokine expression.

These markers help researchers study Th17 cell function in autoimmune diseases, chronic inflammation, and host defense. Understanding Th17 marker expression supports the development of targeted therapies and enhances insights into immune system dynamics.

CD3

CD3 is a vital part of the T cell receptor complex and is found on all mature T cells, including Th17 cells. It is involved in signaling during antigen recognition. Although CD3 is not exclusive to Th17 cells, it is used together with markers like CD4, CD194, and IL-17A to identify this subset. CD3 helps researchers determine the total T cell population before further analyzing Th17 responses in inflammation, autoimmunity, and mucosal immunity.

Figure 30. Immunohistochemistry (Formalin/PFA-fixed paraffin-embedded sections) - Anti-CD3 epsilon antibody (ab5690).

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CD194

CD194, or CCR4, is a chemokine receptor expressed on subsets of Th17 T cells. It helps guide these cells to sites of inflammation by responding to chemokine gradients. In Th17 profiling, CD194 is used alongside markers like CD3, CD4, and IL-17A to identify and track Th17 cell populations. Its expression supports research into autoimmune diseases, mucosal immunity, and chronic inflammation by highlighting Th17 cell localization and function.

Figure 30. Immunocytochemistry/ Immunofluorescence - Anti-CCR4 antibody [EPR27421-23] (ab318958).

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IL-17A

IL-17A is a proinflammatory cytokine produced by Th17 T cells and is widely used as a functional marker for this subset. It promotes neutrophil recruitment and enhances tissue inflammation during immune responses. IL-17A expression is typically assessed alongside markers like CD3, CD4, and CD194 to identify Th17 cells. Its role in autoimmune diseases, mucosal defense, and chronic inflammation makes IL-17A a valuable target in immunological research and therapeutic development.

Figure 31. Immunohistochemistry (Formalin/PFA-fixed paraffin-embedded sections) - Anti-IL-17A antibody (ab79056).

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TGFβ

Transforming growth factor beta (TGFβ) is a cytokine involved in the early differentiation of Th17 T cells. In combination with interleukin-6 (IL-6), TGFβ promotes the development of Th17 cells from naive CD4+ T cells. While not a surface marker, TGFβ is a key signaling molecule used to induce IL-17A expression. Researchers use TGFβ in vitro to model Th17 polarization and study its role in inflammation, autoimmunity, and mucosal immunity.

Figure 32. Immunohistochemistry (Formalin/PFA-fixed paraffin-embedded sections) - Anti-TGF beta 1 antibody [EPR21143] (ab215715).

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IL-6

Interleukin-6 (IL-6) is a cytokine that supports the differentiation of Th17 T cells from naive CD4+ T cells, particularly when combined with TGFβ. While IL-6 is not a surface marker, it plays a signaling role in promoting IL-17A expression and Th17 lineage commitment. Researchers use IL-6 in experimental models to study Th17 polarization and its involvement in autoimmune diseases, chronic inflammation, and mucosal immunity.

Figure 33. Immunocytochemistry/ Immunofluorescence - Anti-IL-6 antibody [EPR21711] (ab233706).

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Follicular helper T (Tfh) cells are a subset of CD4+ T cells that support B cell maturation and antibody production. These cells are typically identified by a combination of surface and intracellular markers. CD3 and CD4 confirm their T cell lineage, while CD185 (CXCR5) guides their migration to B cell follicles. CD183 (CXCR3) is often used to define Tfh subsets with Th1-like characteristics. IL-21, a cytokine produced by Tfh cells, plays a role in B cell differentiation and germinal center formation.

These markers are commonly used in flow cytometry and immunohistochemistry to study immune responses in health and disease. Tfh cells have been linked to autoimmune conditions and lymphoproliferative disorders, making their identification valuable in both research and clinical settings. Understanding the expression patterns of these markers helps researchers explore immune regulation and develop targeted therapies.

CD3

CD3 is a key part of the T cell receptor complex and is commonly used to identify T cells, including follicular helper T (Tfh) cells. Although CD3 doesn't differentiate Tfh cells from other T cell subsets, it verifies their lineage as mature T lymphocytes. When combined with markers like CD4 and CXCR5, CD3 enables researchers to isolate and study Tfh cells in immune profiling, vaccine development, and autoimmune disease research.

Figure 34. Multiplex immunohistochemistry - Anti-CD3 epsilon antibody [CAL57] (ab237721).

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CD4

CD4 is a surface glycoprotein expressed on helper T cells, including follicular helper T (Tfh) cells. It plays a role in T cell receptor signaling and is widely used to identify T cell subsets in immunological studies. In Tfh cells, CD4 expression is combined with markers like CXCR5 and PD-1 to define their phenotype. CD4+ Tfh cells support B cell responses within germinal centers, contributing to antibody production and immune memory.

Figure 35. Immunohistochemistry (Formalin/PFA-fixed paraffin-embedded sections) - Anti-CD4 antibody [EPR19514] (ab183685).

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CD185

CD185, or CXCR5, is a chemokine receptor that guides follicular helper T (Tfh) cells to B cell follicles within secondary lymphoid tissues. It is a defining surface marker distinguishing Tfh cells from other CD4+ T cell subsets. CD185 expression enables Tfh cells to interact with B cells during germinal center reactions, supporting antibody production and immune memory. Researchers often use CD185 in combination with PD-1 and ICOS to study Tfh cell function and distribution.

Figure 36. Immunohistochemistry (Formalin/PFA-fixed paraffin-embedded sections) - Anti-CXCR5 antibody [EPR23463-30] (ab254415).

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CD183

CD183, also known as CXCR3, is a chemokine receptor expressed on certain subsets of follicular helper T (Tfh) cells. It is often used to identify Th1-like Tfh cells, which may influence the type of antibody response generated. CD183+ Tfh cells have been observed in both germinal centers and circulation, where they can support B cell activation. Researchers use CD183 expression to explore Tfh cell diversity and its implications in infection, vaccination, and autoimmune conditions.

Figure 37. Immunohistochemistry (Formalin/PFA-fixed paraffin-embedded sections) - Anti-CXCR3 antibody [EPR25373-32] (ab288437).

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IL-21

IL-21 is a cytokine produced by follicular helper T (Tfh) cells that supports B cell activation and antibody production. It plays a role in germinal center formation by promoting B cell proliferation and survival. IL-21 also influences the balance between Tfh cells and follicular regulatory T cells, shaping the quality of humoral responses. Researchers use IL-21 expression as a functional marker to study Tfh cell activity in vaccination, infection, and autoimmune disease models.

Figure 38. Immunocytochemistry/ Immunofluorescence - Anti-IL-21 antibody (ab5978).

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Regulatory T (Treg) cells are a specialized subset of CD4+ T cells that help maintain immune tolerance and prevent overactive immune responses. They are commonly identified by high expression of CD25 and low expression of CD127. The transcription factor FoxP3 is a key intracellular marker used to confirm Treg identity. CD152 (CTLA-4) is another marker associated with their suppressive function.

Treg cells exert their effects through cytokines such as TGFβ and IL-10, which help dampen inflammation. IL-12 can influence Treg plasticity under certain conditions. STAT5 signaling is involved in the development and maintenance of Treg cells, particularly in response to IL-2. These markers are widely used in immunological research to study Treg cell function in autoimmunity, cancer, and transplantation.

CD4

CD4 is a surface glycoprotein expressed on helper T cells, including regulatory T (Treg) cells. It plays a role in T cell receptor signaling and immune coordination. In Treg cells, CD4 is used alongside markers like CD25 and FoxP3 to define their identity and function. CD4+ Treg cells contribute to immune tolerance by suppressing overactive immune responses. Researchers use CD4 expression to isolate and study Treg populations in autoimmune disease, cancer, and transplantation research.

Figure 39. Immunohistochemistry (Formalin/PFA-fixed paraffin-embedded sections) - Anti-CD4 antibody [EPR6855] (ab133616).

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CD25

CD25, the alpha chain of the interleukin-2 receptor, is a key surface marker used to identify regulatory T (Treg) cells. It is typically expressed at high levels on CD4+ T cells with immunosuppressive function. CD25 works with IL-2 signaling to support Treg cell survival and activity. When combined with markers like CD127 and FoxP3, CD25 helps distinguish Treg cells from other T cell subsets in studies of immune tolerance, inflammation, and therapeutic modulation.

Figure 40. Immunohistochemistry (Formalin/PFA-fixed paraffin-embedded sections) - Anti-IL-2 Receptor alpha antibody [EPR22588-18] (ab227834).

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CD127

CD127, the alpha chain of the interleukin-7 receptor, is commonly used to distinguish regulatory T (Treg) cells from conventional T cells. Treg cells typically express low or absent levels of CD127, which helps differentiate them when combined with high CD25 and FoxP3 expression. This inverse relationship supports more accurate identification of Treg populations in flow cytometry. CD127 expression is also studied in the context of immune activation, tolerance, and therapeutic targeting in autoimmune and inflammatory diseases.

Figure 41. Flow Cytometry - Anti-CD127 antibody [EPR22835-249] (ab255816).

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CD152

CD152, also known as CTLA-4, is a surface protein expressed on regulatory T (Treg) cells that contributes to their immunosuppressive activity. It competes with CD28 for binding to B7 molecules on antigen-presenting cells, helping to limit T cell activation. CD152 expression is often used alongside CD25 and FoxP3 to identify functional Treg cells. Its role in immune regulation makes it a focus in studies of autoimmunity, cancer immunotherapy, and transplant tolerance.

Figure 42. Immunohistochemistry (Formalin/PFA-fixed paraffin-embedded sections) - Anti-CTLA4 antibody [CAL49] (ab237712).

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TGFβ

Transforming growth factor beta (TGFβ) is a cytokine associated with the development and function of regulatory T (Treg) cells. It supports the induction of FoxP3 expression in naïve CD4+ T cells, promoting their differentiation into Treg cells. TGFβ also contributes to immune suppression by modulating inflammatory responses. Its presence is often used to assess Treg activity in various disease models, including autoimmunity, cancer, and chronic inflammation.

Figure 43. Western blot - Anti-TGF beta 1 antibody [EPR18163] (ab179695).

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IL-10

Interleukin-10 (IL-10) is an anti-inflammatory cytokine produced by regulatory T (Treg) cells that helps control immune responses. It limits the activity of antigen-presenting cells and effector T cells, contributing to immune tolerance. IL-10 expression is often used as a functional marker to assess Treg cell activity in various disease settings. Its role in modulating inflammation makes it a focus in studies of autoimmunity, allergy, and chronic infection.

Figure 44. Immunocytochemistry/ Immunofluorescence - Anti-IL-10 antibody [EPR1114] (ab133575).

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IL-12

Interleukin-12 (IL-12) is a pro-inflammatory cytokine that can influence the stability and function of regulatory T (Treg) cells. While not a classical Treg marker, IL-12 exposure may reduce FoxP3 expression and shift Treg cells toward a more effector-like phenotype. Studying IL-12 in the context of Treg plasticity helps researchers understand immune regulation in chronic inflammation, infection, and cancer. Its role in shaping Treg responses is relevant for therapeutic strategies targeting immune balance.

Figure 45. Immunocytochemistry/ Immunofluorescence - Anti-IL-12B antibody [EPR5739] (ab133752).

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FOXP3

FOXP3 is a transcription factor widely recognized as a defining marker of regulatory T (Treg) cells. It plays a central role in the development, stability, and suppressive function of Treg cells. High FOXP3 expression is used to distinguish Treg cells from other CD4+ T cell subsets in both human and mouse models. Researchers rely on FOXP3 as a key indicator of Treg lineage in studies of immune tolerance, autoimmunity, and therapeutic modulation.

Figure 46. Flow Cytometry (Intracellular) - Anti-FOXP3 antibody [EPR22102-37] (ab215206).

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STAT5

Signal transducer and activator of transcription 5 (STAT5) is a transcription factor activated by interleukin-2 signaling. It plays a role in the development and maintenance of regulatory T (Treg) cells by promoting FOXP3 expression. STAT5 activity supports Treg cell survival and function, making it a useful marker in studies of immune regulation. Researchers often assess STAT5 phosphorylation to evaluate Treg responses in autoimmune conditions, cancer, and immunotherapy models.

Signal transducer and activator of transcription 5 (STAT5) is a transcription factor activated by interleukin-2 signaling. It plays a role in the development and maintenance of regulatory T (Treg) cells by promoting FOXP3 expression. STAT5 activity supports Treg cell survival and function, making it a useful marker in studies of immune regulation. Researchers often assess STAT5 phosphorylation to evaluate Treg responses in autoimmune conditions, cancer, and immunotherapy models.

Figure 47. Immunohistochemistry (Formalin/PFA-fixed paraffin-embedded sections) - Anti-STAT5 (phospho Y694) antibody [E208] (ab32364).

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Central memory T (Tcm) cells are a subset of memory T cells that contribute to long-term immune protection. These cells are characterized by the expression of CD3, a pan-T cell marker, along with CD62L (L-selectin) and CD197 (CCR7). CD62L and CD197 enable Tcm cells to home to secondary lymphoid organs, where they can rapidly respond to antigen re-exposure.

Tcm cells display a high proliferative capacity and can differentiate into effector T cells upon activation. Their marker profile distinguishes them from effector memory T cells, which lack CD62L and CD197 expression. Researchers use these markers in flow cytometry to study memory T cell dynamics in infection, vaccination, and immunotherapy. Understanding Tcm cell behavior helps inform strategies for enhancing immune memory and designing long-lasting vaccines.

CD3

CD3 is a fundamental component of the T cell receptor complex and is expressed on all mature T cells, including central memory T (Tcm) cells. It is involved in T cell activation and signal transduction processes. Although CD3 alone does not differentiate Tcm cells from other T cell subsets, it is utilized in conjunction with markers such as CD62L and CD197 to identify and analyze Tcm populations within the contexts of immune monitoring, vaccine research, and T cell-based therapeutics.

Figure 48. Immunohistochemistry (Formalin/PFA-fixed paraffin-embedded sections) - Anti-CD3 antibody [CD3-12] (ab11089).

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Effector memory T (Tem) cells are a subset of memory T cells that respond quickly to previously encountered antigens. These cells are typically identified by the expression of CD45RO in humans or CD44 in mice, both of which are associated with antigen experience. CD45, a pan-leukocyte marker, exists in different isoforms, and its expression pattern helps distinguish naïve from memory T cells.

Tem cells lack lymphoid homing markers like CD62L and CD197, allowing them to circulate through peripheral tissues. CD44 expression is elevated in Tem cells, reflecting their activation history and readiness to exert effector functions. Researchers use these markers to study immune memory, vaccine efficacy, and T cell-mediated immunity in infection and cancer. Understanding Tem cell profiles supports the development of targeted immunotherapies and monitoring of immune health.

CD45

CD45 is a transmembrane protein tyrosine phosphatase expressed on all leukocytes, including T cells. In effector memory T (Tem) cells, CD45 is typically present in its RO isoform (CD45RO), which is associated with antigen-experienced cells. This contrasts with the RA isoform (CD45RA) found on naïve T cells. CD45RO expression helps identify Tem cells in flow cytometry, supporting research into immune memory, infection response, and the development of T cell-based immunotherapies.

Figure 51. Immunocytochemistry/ Immunofluorescence - Anti-CD45 antibody [EP322Y] (ab40763).

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CD62L

CD62L, also known as L-selectin, is a surface adhesion molecule expressed on central memory T (Tcm) cells. It enables these cells to home to secondary lymphoid organs by mediating entry through high endothelial venules. CD62L expression, along with CD197, helps distinguish Tcm cells from effector memory T cells. Researchers use CD62L as a marker in flow cytometry to study T cell migration, immune memory, and responses to vaccination or immunotherapy.

Figure 49. Flow Cytometry - Anti-CD62L antibody [EPR23565-109] (ab245239).

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CD44

CD44 is a cell surface glycoprotein involved in cell adhesion and migration. It is highly expressed on effector memory T (Tem) cells, distinguishing them from naïve T cells. CD44 expression reflects prior antigen exposure and supports tissue homing and immune surveillance. In flow cytometry, CD44 is used alongside other markers to identify Tem cells in studies of infection, inflammation, and immunotherapy. Its role in T cell trafficking makes it a valuable marker in immune profiling.

Figure 52. Immunohistochemistry (Formalin/PFA-fixed paraffin-embedded sections) - Anti-CD44 antibody [EPR18668] (ab189524).

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CD197

CD197, also known as CCR7, is a chemokine receptor expressed on central memory T (Tcm) cells. It guides these cells to lymphoid tissues by responding to chemokines CCL19 and CCL21. CD197 expression, along with CD62L, helps define the Tcm phenotype and distinguishes it from effector memory T cells. Researchers use CD197 in immunophenotyping to study T cell trafficking, immune surveillance, and long-term memory responses in infection, vaccination, and immunotherapy research.

Figure 50. Immunohistochemistry (Frozen sections) - Anti-CCR7 antibody [EPR23192-57] - BSA and Azide free (ab272938).

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