CD4
GeneName
CD4
Summary
CD4, also known as CD40, CD-4, or hCD4, is a 51 kDa glycoprotein primarily expressed on the surface of T helper cells, monocytes, and dendritic cells. It is a vital component of the immune system, functioning as a co-receptor for the T cell receptor complex, facilitating the recognition of antigens presented by MHC class II molecules. CD4 is involved in various cellular processes, including T cell activation, differentiation, and proliferation, and plays a role in signalling pathways that regulate immune responses. It is localised in several cellular compartments, including the plasma membrane, endoplasmic reticulum, and clathrin-coated endocytic vesicles, highlighting its dynamic role in cellular signalling and immune function.
Importance
CD4 is relevant to: - The adaptive immune response, as it enhances T cell activation and differentiation, crucial for effective immune defence. - The regulation of immune responses to pathogens, particularly Gram-negative bacteria, through its role in helper T cell functions. - Studies of HIV infection, as CD4 serves as a primary receptor for the virus, making it significant in understanding viral entry and pathogenesis. - Research into autoimmune diseases, where CD4+ T cells can contribute to dysregulated immune responses and tissue damage.
Top Products
For researchers investigating CD4, we recommend two excellent primary antibodies. The first is the well-cited Anti-CD4 antibody [EPR6855] (ab133616), which has garnered 479 citations, reflecting its strong reputation in the field. This antibody is versatile, suitable for flow cytometry (FC), immunohistochemistry (IHC), immunocytochemistry (ICC), and western blotting (WB). Additionally, we offer the recombinant antibody, Anti-CD4 antibody [SP35] (ab213215). This product is validated for use in flow cytometry (FC), immunohistochemistry (IHC), and immunocytochemistry (ICC), making it a reliable choice for researchers seeking consistency in their experiments. With 21 citations, it is also gaining traction in the research community. Together, these antibodies provide robust options for studying CD4 effectively. The Human CD4 ELISA Kit (ab234569) is a reliable option for researchers looking to measure CD4 levels in their samples.
Abcam Product Citation Summary
The data indicates that CD4 antibodies are widely used in various applications, including Western blotting, immunohistochemistry, and immunofluorescence, across different human tissues and conditions. Studies focus on immune responses in contexts such as HIV-1, sarcoidosis, multiple sclerosis, and breast cancer, highlighting the importance of CD4 in immune cell infiltration and T cell activity.
Abcam Product Citation Table
Domain
The Ig-like V-type domain mediates the interaction with MHCII.
Function
Integral membrane glycoprotein that plays an essential role in the immune response and serves multiple functions in responses against both external and internal offenses. In T-cells, functions primarily as a coreceptor for MHC class II molecule:peptide complex. The antigens presented by class II peptides are derived from extracellular proteins while class I peptides are derived from cytosolic proteins. Interacts simultaneously with the T-cell receptor (TCR) and the MHC class II presented by antigen presenting cells (APCs). In turn, recruits the Src kinase LCK to the vicinity of the TCR-CD3 complex. LCK then initiates different intracellular signaling pathways by phosphorylating various substrates ultimately leading to lymphokine production, motility, adhesion and activation of T-helper cells. In other cells such as macrophages or NK cells, plays a role in differentiation/activation, cytokine expression and cell migration in a TCR/LCK-independent pathway. Participates in the development of T-helper cells in the thymus and triggers the differentiation of monocytes into functional mature macrophages.
(Microbial infection) Primary receptor for human immunodeficiency virus-1 (HIV-1) (PubMed:12089508, PubMed:16331979, PubMed:2214026, PubMed:9641677). Down-regulated by HIV-1 Vpu (PubMed:17346169). Acts as a receptor for Human Herpes virus 7/HHV-7 (PubMed:7909607).
Involvement in disease
Immunodeficiency 79
IMD79
An autosomal recessive disorder characterized by childhood onset of recurrent and recalcitrant skin warts due to uncontrolled viral infection with human papillomavirus (HPV). Some patients may also have recurrent respiratory infections. Laboratory studies show a complete absence of CD4+ T cells.
None
The disease is caused by variants affecting the gene represented in this entry.
Post-translational modifications
Palmitoylation and association with LCK contribute to the enrichment of CD4 in lipid rafts.
Phosphorylated by PKC; phosphorylation at Ser-433 plays an important role for CD4 internalization.
Tissue Specificity
Highly expressed in T-helper cells. The presence of CD4 is a hallmark of T-helper cells which are specialized in the activation and growth of cytotoxic T-cells, regulation of B cells, or activation of phagocytes. CD4 is also present in other immune cells such as macrophages, dendritic cells or NK cells.
Cellular localization
- Cell membrane
- Single-pass type I membrane protein
- Localizes to lipid rafts (PubMed:12517957, PubMed:9168119). Removed from plasma membrane by HIV-1 Nef protein that increases clathrin-dependent endocytosis of this antigen to target it to lysosomal degradation. Cell surface expression is also down-modulated by HIV-1 Envelope polyprotein gp160 that interacts with, and sequesters CD4 in the endoplasmic reticulum.
Alternative names
CD4, T-cell surface glycoprotein CD4, T-cell surface antigen T4/Leu-3
Database links
Other research areas
- Immunology & Infectious Disease