HB5 recognizes CD21, a type I membrane glycoprotein. Expression of CD21 in humans is found on B cells, follicular dendritic cells, subsets of epithelial cells, and thymic T cells. The primary function attributed to CD21 has been to amplify the B cell receptor (BCR)-mediated signal transduction in response to antigen recognition. To enhance the BCR mediated activation, CD21 associates with CD19 and CD81 in a B cell–specific signal transduction complex, where interaction of BCR with CR2/CD19 amplifies the signals. In addition, CD21 serves as a receptor for split products of complement protein C3, the gp350/220 viral coat protein of the EBV and the immunoregulatory protein CD23.

Alternative names

Complement Receptor 2 (CR2), Complement 3d Receptor

Technical specifications

  • Antigen: CD21
  • Clone: HB5
  • Isotype: mouse IgG2a
  • Alternative names of antigen: Complement Receptor 2 (CR2), Complement 3d Receptor
  • Distribution of antigen: B cells, dendritic cells, T cells
  • Product format: Reagents are supplied in buffer containing stabilizer and 0.05% sodium azide.
  • Storage: Store protected from light at 2–8 °C (36–46 °F). Do not freeze.
  • Available conjugates: VioBlue, PE
  • Selected references

    1. Barrington, R. A. et al. (2005) CD21/CD19 coreceptor signaling promotes B cell survival during primary immune responses. J. Immunol. 175: 2589-2867
    2. Cherukuri, A. et al. (2001) The role of the CD19/CD21 complex in B cell processing and presentation of complement-tagged antigens. J. Immunol. 167: 163-172
    3. Tedder, TF. et al. (1984) Expression of C3d receptors during human B cell differentiation: immunofluorescence analysis with the HB-5 monoclonal antibody. J. Immunol. 133 (2): 678-683
    4. Braun, M. et al. (1998) Human B and T lymphocytes have similar amounts of CD21 mRNA, but differ in surface expression of the CD21 glycoprotein. Int. Immunol. 10: 1197-1202
    5. Stelzer GT et al. (1997) U.S.-Canadian consensus recommendations on the immunophenotypic analysis of hematologic neoplasia by flow cytometry: standardization and validation of laboratory procedures. Cytometry 30(5): 214-230
    6. Rothe, G et al. (2012) Consensus protocol for the flow cytometric Immunophenotyping of hematopoietic malignancies. Leukemia 10(5): 877-895
    7. van Dongen, J. J. M. et al. (2012) EuroFlow antibody panels for standardized n-dimensional flow cytometric immunophenotyping of normal, reactive and malignant leukocytes. Leukemia 26(9): 1908-1975
    8. Roberts, M. L. et al. (1996) Epstein—Barr virus binding to CD21, the virus receptor, activates resting B cells via an intracellular pathway that is linked to B cell infection. Virology 77: 3077-3085
    9. Clinical and Laboratory Standards Institute (CLSI) (2007) Clinical Flow Cytometric Analysis of Neoplastic Hematolympoid Cells, CLSI document H43-A2 (ISBN 1-56238-635-2) CLSI; Approved Guideline - Second Edition
    10. Clinical and Laboratory Standards Institute (CLSI) (2007) Enumeration of immunologically defined cell populations by flow cytometry, CLSI document H42-A2 (ISBN 1-56238-640-9) CLSI; Approved Guideline - Second Edition
    11. Reinherz, E. L. et al. (eds) Leucocyte typing II. Springer
  • Certificates

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