• Product name
    Anti-MHC Class II antibody [MRC OX-6]
    See all MHC Class II primary antibodies
  • Description
    Mouse monoclonal [MRC OX-6] to MHC Class II
  • Host species
  • Specificity
    This antibody recognises a monomorphic determinant of the rat I-A antigen present on B lymphocytes, dendritic cells, some macrophages and certain epithelial cells. The antibody cross-reacts with certain mouse strains of MHC haplotypes k and s and analysis of recombinant strains showed that the determinants mapped to the I-A region of the mouse MHC.
  • Tested applications
    Suitable for: WB, ICC, IHC-P, ICC/IF, Flow Cyt, IHC-Fr, IHC (PFA fixed)more details
  • Species reactivity
    Reacts with: Rat
    Predicted to work with: Mouse
  • Immunogen

    Thymocyte membrane glycoprotein (Rat).

  • Positive control
    • This antibody gave a positive result in IHC in the following FFPE tissue: Rat normal spleen.
  • General notes

    This antibody clone is manufactured by Abcam.

    If you require this antibody in a particular buffer formulation or a particular conjugate for your experiments, please contact orders@abcam.com or you can find further information here.


  • Form
  • Storage instructions
    Shipped at 4°C. Store at +4°C short term (1-2 weeks). Upon delivery aliquot. Store at -20°C long term.
  • Storage buffer
    pH: 7.4
    Preservative: 0.02% Sodium azide
    Constituents: PBS, 6.97% L-Arginine
  • Concentration information loading...
  • Purity
    Immunogen affinity purified
  • Clonality
  • Clone number
    MRC OX-6
  • Myeloma
  • Isotype
  • Research areas


Our Abpromise guarantee covers the use of ab23990 in the following tested applications.

The application notes include recommended starting dilutions; optimal dilutions/concentrations should be determined by the end user.

Application Abreviews Notes
WB Use at an assay dependent concentration. Predicted molecular weight: 29 kDa.
ICC Use at an assay dependent concentration.
IHC-P Use at an assay dependent concentration.
ICC/IF Use at an assay dependent concentration.
Flow Cyt Use 10µl for 106 cells.

ab170190 - Mouse monoclonal IgG1, is suitable for use as an isotype control with this antibody.

IHC-Fr Use at an assay dependent concentration.
IHC (PFA fixed) 1/100.


  • Function
    Binds peptides derived from antigens that access the endocytic route of antigen presenting cells (APC) and presents them on the cell surface for recognition by the CD4 T-cells. The peptide binding cleft accomodates peptides of 10-30 residues. The peptides presented by MHC class II molecules are generated mostly by degradation of proteins that access the endocytic route, where they are processed by lysosomal proteases and other hydrolases. Exogenous antigens that have been endocytosed by the APC are thus readily available for presentation via MHC II molecules, and for this reason this antigen presentation pathway is usually referred to as exogenous. As membrane proteins on their way to degradation in lysosomes as part of their normal turn-over are also contained in the endosomal/lysosomal compartments, exogenous antigens must compete with those derived from endogenous components. Autophagy is also a source of endogenous peptides, autophagosomes constitutively fuse with MHC class II loading compartments. In addition to APCs, other cells of the gastrointestinal tract, such as epithelial cells, express MHC class II molecules and CD74 and act as APCs, which is an unusual trait of the GI tract. To produce a MHC class II molecule that presents an antigen, three MHC class II molecules (heterodimers of an alpha and a beta chain) associate with a CD74 trimer in the ER to form an heterononamer. Soon after the entry of this complex into the endosomal/lysosomal system where antigen processing occurs, CD74 undergoes a sequential degradation by various proteases, including CTSS and CTSL, leaving a small fragment termed CLIP (class-II-associated invariant chain peptide). The removal of CLIP is facilitated by HLA-DM via direct binding to the alpha-beta-CLIP complex so that CLIP is released. HLA-DM stabilizes MHC class II molecules until primary high affinity antigenic peptides are bound. The MHC II molecule bound to a peptide is then transported to the cell membrane surface. In B cells, the interaction between HLA-DM and MHC class II molecules is regulated by HLA-DO. Primary dendritic cells (DCs) also to express HLA-DO. Lysosomal miroenvironment has been implicated in the regulation of antigen loading into MHC II molecules, increased acidification produces increased proteolysis and efficient peptide loading.
  • Sequence similarities
    Belongs to the MHC class II family.
    Contains 1 Ig-like C1-type (immunoglobulin-like) domain.
  • Cellular localization
    Cell membrane. Endoplasmic reticulum membrane. Golgi apparatus > trans-Golgi network membrane. Endosome membrane. Lysosome membrane. The MHC class II complex transits through a number of intracellular compartments in the endocytic pathway until it reaches the cell membrane for antigen presentation.
  • Information by UniProt
  • Database links
  • Alternative names
    • D6S221E antibody
    • DMA antibody
    • DMB antibody
    • DP beta 1 antibody
    • DP beta 1 chain antibody
    • DP(W4) beta chain antibody
    • DPB 1 antibody
    • DPB1 antibody
    • DPB1_HUMAN antibody
    • DRB antibody
    • H2Ea antibody
    • HLA class II histocompatibility antigen antibody
    • HLA class II histocompatibility antigen DM beta chain antibody
    • HLA class II histocompatibility antigen, DP beta 1 chain antibody
    • HLA class II histocompatibility antigen, DP(W4) beta chain antibody
    • HLA DMB antibody
    • HLA DP1A antibody
    • HLA DPB1 antibody
    • HLA SB alpha chain antibody
    • HLA-A antibody
    • HLA-A histocompatibility type antibody
    • HLA-DP antibody
    • HLA-DP histocompatibility type, beta-1 subunit antibody
    • HLA-DP1B antibody
    • HLA-DPB antibody
    • HLA-DPB1 antibody
    • HLADM antibody
    • HLADP1B antibody
    • HLASB antibody
    • HLASB histocompatibility type antibody
    • Human MHC class II HLA SB alpha antibody
    • LA class II histocompatibility antigen DP alpha 1 chain antibody
    • Major histocompatibility complex class II antibody
    • Major histocompatibility complex class II DP alpha 1 antibody
    • Major histocompatibility complex class II DP beta 1 antibody
    • Major histocompatibility complex, class I, A antibody
    • MHC class II antigen DMB antibody
    • MHC class II antigen DPB1 antibody
    • MHC class II DP3 alpha antibody
    • MHC class II DPA1 antibody
    • MHC class II HLA-DP-beta-1 antibody
    • MHC DPB1 antibody
    • MHC HLA DPB1 antibody
    • PLT1 antibody
    • Primed lymphocyte test 1 antibody
    • RING6 antibody
    • RING7 antibody
    see all


  • Immunohistochemistical detection of MHC Class II using antibody ab23990 on PFA-fixed rat spleen tissue sections. Antibody diluted at 1/100 and incubated for2 hours in  TBS/BSA/Tween/azide. Secondary antibody: anti mouse IgG conjugated to biotin (1/100). After dissection of spleen from PFA-perfused specimen it was sampled and further immersion-fixed for two Hrs. After subsequent immersion in 30% Sucrose, specimens were snap-frozen. Before immunostaining, the 8 micron sections were placed in a 60 degree C oven for 60 mins to enhance adhesion. The submitted image shows white pulp (PALS) and a small area of red pulp (RP-upper left). The Periarteriolar Sheath (PALS) with it's Central Arteriole/artery (CA)shows many positive cells (B-lymphocytes and Macrophages) and negative lymphocytes (T-cells?). The Marginal Sinus (MS) is clearly seen between the PALS and the Marginal Zone (MZ). There is a clear Germinal Centre (GS) in this image. Lymphoid tissue is not my

    See Abreview

  • ab23990 staining MHC Class II in Rat spleen tissue by Immunohistochemistry (Frozen sections). The sections were fixed in PFA prior to blocking with 10% serum for 20 minutes at 24°C. The primary antibody was diluted 1/100 in PBS and incubated with the sample for 16 hours at 4°C. An Alexa Fluor® 488-conjugated donkey anti-mouse polyclonal was used as the secondary antibody, diluted 1/1000 for 1 hour at room temperature. Counterstained with Hoechst 33258 (blue) for 10 minutes at room temperature

    See Abreview

  • IHC image of MHC Class II staining in Rat normal spleen formalin fixed paraffin embedded tissue section, performed on a Leica BondTM system using the standard protocol F. The section was pre-treated using heat mediated antigen retrieval with sodium citrate buffer (pH6, epitope retrieval solution 1) for 20 mins. The section was then incubated with ab23990, 10µg/ml, for 15 mins at room temperature and detected using an HRP conjugated compact polymer system. DAB was used as the chromogen. The section was then counterstained with haematoxylin and mounted with DPX.

    For other IHC staining systems (automated and non-automated) customers should optimize variable parameters such as antigen retrieval conditions, primary antibody concentration and antibody incubation times.


This product has been referenced in:
  • Shall G  et al. Effects of Passage Number and Differentiation Protocol on the Generation of Dopaminergic Neurons from Rat Bone Marrow-Derived Mesenchymal Stem Cells. Int J Mol Sci 19:N/A (2018). Flow Cyt ; Rat . Read more (PubMed: 29498713) »
  • Parajuli P  et al. Twist1 Activation in Muscle Progenitor Cells Causes Muscle Loss Akin to Cancer Cachexia. Dev Cell 45:712-725.e6 (2018). Read more (PubMed: 29920276) »
See all 23 Publications for this product

Customer reviews and Q&As

1-10 of 12 Abreviews or Q&A

Immunocytochemistry/ Immunofluorescence
Mouse Cell (Brain, Hypothalamus)
Yes - 0.1% Tween-20 in PBS
Brain, Hypothalamus
Blocking step
BSA as blocking agent for 40 minute(s) · Concentration: 1% · Temperature: 25°C

Miss. Chia-Li Lin

Verified customer

Submitted Nov 19 2015


Thank you for contacting us.

We do sell this specific clone to MHC II. The product number for this antibody is ab23990. It is sold at 125ug size at a concentration of 1mg/ml. These are currently in stock both in the US and at our other offices worldwide. We ship overnight for next day delivery. More information may be found at this location:


I hope this information is helpful to you. Please do not hesitate to contact us if you need any more advice or information.

Free Rabbit monoclonal antibody with any purchase of a primary antibody, while stocks last! Quote “RABMAB-XBSMG” in your next primary antibody order. For more information, visit the following link: https://www.abcam.com/index.html?pageconfig=resource&rid=15447

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Thank you for your enquiry.

I would like to reassure you that our antibodies have all been tested successfully and would be covered by our guarantee in the applications listed on the datasheets. Therefore, any antibody tested in the species and application you are using should be suitable for your applications.

Also, although we produce many in-house antibodies, we obtain other antibodies from a wide range of sources. Therefore, comparison experiments will not often have been done.

If you wish to be more certain, I can suggest choosing the antibody that has been best characterized. By this I mean the antibody that has been tested in the most applications and has the most data available (on the datasheet).

In regard to your concerns about ab15690 Anti-Iba1 antibody [1022-5], we do offer another Anti-Iba1 which has been raised in goat and has a number of referenced publications, Abreviews and support data. I would recommend this product as an alternative to ab15690.


I look forward to hearing from you. Should you have any further questions please do not hesitate to ask.

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Abcam guarantees this product to work in the species/application used in this Abreview.
Rat Cultured Cells (33B)
Blocking step
Serum as blocking agent for 30 minute(s) · Concentration: 10% · Temperature: 24°C

Abcam user community

Verified customer

Submitted Jul 06 2012

Abcam guarantees this product to work in the species/application used in this Abreview.
Immunocytochemistry/ Immunofluorescence
Rat Cell (B50 Neuroblastoma Cell line)
B50 Neuroblastoma Cell line
Blocking step
Serum as blocking agent for 20 minute(s) · Concentration: 10% · Temperature: 24°C

Abcam user community

Verified customer

Submitted Jun 21 2012


Thanks again for your call last week amd for your question about this antibody. I sincerely apologize but I just received further information from the lab, and the last email I sent you contained misinformation. This antibody has actually been tested in several strains of mice, and it does not appear to be reactive with the D,B, or Q haplotypes. I found an order assume is your order. If you have already opened this antibody, I can issue an immediate refund. If you have not opened the vial I can exchange it for a different MHC class II antibody or you can just return it for a refund. Again, I am very sorry for this error, and I look forward to hearing from you so we can resolve this promptly. Please let me know if you have any questions or if there is anything else that we can do for you.  

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Thank you for your call yesterday and for your patience while I have been in touch with the lab. I have attached a document that shows what strains have been tested with ab23990. According to the lab, we have not tested C57/Bl6, however every strain tested was positive. Since this antibody recognizes a monomorphic determinant, they are confident that it will work with the other strains as well. I hope this information will be useful, but if you need any further information please let me know and I'll be happy to help.    

Read More
Abcam guarantees this product to work in the species/application used in this Abreview.
Immunohistochemistry (Frozen sections)
Rat Tissue sections (Spleen)
Blocking step
Serum as blocking agent for 20 minute(s) · Concentration: 10% · Temperature: 24°C

Abcam user community

Verified customer

Submitted Sep 23 2011


Thank you for your patience. I have received the following explanation from the lab that will hopefully help to answer your questions: Please see below for a breakdown of rat and mouse MHC molecules. Rat MHC Class II molecules are RT1.B, RT1.D and RT1.H. Class I molecules are simply RT1. Mouse MHC class II molecules are I-A and I-E which happen to be very similar to the rat RT1.B and RT1.D but are named differently in each species. ab23990 is described as mouse anti-rat MHC Class II RT1B, but also recognizes mouse MHC class II I-A in mice with haplotypes k and s. And ab8351 is reacting with RT1B. Regarding your question 1: The antigens being referred to are incorrect. Rat MHC Class II molecules are RT1.B, RT1.D and RT1.H. There is no rat I-A or I-B. Regarding question 2: The antibody ab23990 is not targeted against MHC Class I molecules. I hope this information is helpful to you. Please do not hesitate to contact us if you need any more advice or information.

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Thank you for your enquiry. Permeabilisation is normally required for intracellular Flow Cytometry as this involves whole cells. However, for immunohistochemistry (whether using fluorescence or HRP), the cells have already been sliced, so further permeabilisation may not be required. We generally recommend acetone fixation as PFA can sometimes be problematic. Would it be possible to try this antibody without permeabilisation as this is likely to be the cause of the issues that you are experiencing? Please find below our recommended protocol for use with frozen sections: http://www.abdserotec.com/support/recommended-protocols-650.html

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1-10 of 12 Abreviews or Q&A


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