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R718 Mouse Anti-Human CD21
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BD OptiBuild™
CR2; Complement receptor type 2; C3DR; EBV-R; Epstein-Barr virus receptor
Human (Tested in Development)
Mouse IgG1, κ
Human CR2 Recombinant Protein
Flow cytometry (Qualified)
0.2 mg/ml
Aqueous buffered solution containing ≤0.09% sodium azide.

Preparation and Storage

Store undiluted at 4°C and protected from prolonged exposure to light. Do not freeze. The monoclonal antibody was purified from tissue culture supernatant or ascites by affinity chromatography. The antibody was conjugated to the dye under optimum conditions that minimize unconjugated dye and antibody.


BD™ CompBeads can be used as surrogates to assess fluorescence spillover (Compensation). When fluorochrome conjugated antibodies are bound to BD CompBeads, they have spectral properties very similar to cells. However, for some fluorochromes there can be small differences in spectral emissions compared to cells, resulting in spillover values that differ when compared to biological controls. It is strongly recommended that when using a reagent for the first time, users compare the spillover on cells and BD CompBead to ensure that BD CompBeads are appropriate for your specific cellular application.

Product Notices

  1. Researchers should determine the optimal concentration of this reagent for their individual applications.
  2. The production process underwent stringent testing and validation to assure that it generates a high-quality conjugate with consistent performance and specific binding activity. However, verification testing has not been performed on all conjugate lots.
  3. An isotype control should be used at the same concentration as the antibody of interest.
  4. Caution: Sodium azide yields highly toxic hydrazoic acid under acidic conditions. Dilute azide compounds in running water before discarding to avoid accumulation of potentially explosive deposits in plumbing.
  5. Alexa Fluor® is a registered trademark of Life Technologies Corporation.
  6. Please refer to to access safety data sheets (SDS).
  7. Please refer to for technical protocols.
  8. This product is provided under an Agreement between BIOTIUM and BD Biosciences. This product, and only in the amount purchased by buyer, may be used solely for buyer’s own internal research, in a manner consistent with the accompanying product literature. No other right to use, sell or otherwise transfer (a) this product, or (b) its components is hereby granted expressly, by implication or by estoppel. This product is for research use only. Diagnostic uses require a separate license from Biotium, Inc. For information on purchasing a license to this product including for purposes other than research, contact Biotium, Inc., 3159 Corporate Place, Hayward, CA 94545, Tel: (510) 265-1027. Fax: (510) 265-1352. Email:
752172 Rev. 1
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CD21 is a 145 kDa transmembrane glycoprotein that is expressed on mature B cells, follicular dendritic cells, a subset of immature thymocytes and on some epithelial cells. CD21 is also known as the C3d Receptor, Complement Receptor 2 (CR2), and the Epstein-Barr Virus receptor, (EBV-R). CD21 is part of a large signal-transduction complex that also includes CD19, CD81 and Leu13. CR2 serves as a receptor for the activation fragments of complement component C3, i.e. C3d, iC3d, and C3dg and C3d-bound antigens and plays a central role in the immune response by amplifying B-cell activation and proliferation. CR2 is also the receptor for EBV by binding its surface glycoprotein gp350/220. Anti-human CR2 hybridomas were generated from Cr2-/-mice (lacking the cr2 gene, that encodes CR2 and CR1 in mice) immunized with the recombinant protein representing the first two amino-terminal short consensus repeats (SRC) of human CR2, SCR1-2. Both the C3d and EBV binding sites of hu CR2 were localized to these sites. Clone 1048 has been reported to specifically react with CR2-expressing cells and to inhibit CR2 interactions with C3 fragments or the EBV surface protein, gp350/220.

The antibody was conjugated to BD Horizon Red 718, which has been developed exclusively for BD Biosciences as a better alternative to Alexa Fluor® 700. BD Horizon Red 718 can be excited by the red laser (628 – 640 nm) and, with an Em Max around 718 nm, it can be detected using a 730/45 nm filter. Due to similar excitation and emission properties, we do not recommend using R718 in combination with APC-R700 or Alexa Fluor® 700.

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The BD Horizon™ Red 718 (R718) Dye is part of the BD red family of dyes. It is a small organic fluorochrome with an excitation maximum (Ex Max) at 695-nm and an emission maximum (Em Max) at 718-nm. Driven by BD innovation, R718 is designed to be excited by the red laser (627–640-nm) and detected using an optical filter centered near 720-nm (e.g., a 720/40-nm bandpass filter). R718 is a brighter alternative to Alexa Fluor™ 700. R718 is also a bright small molecule alternative to APC-R700 with lower spread into the APC detector. Please ensure that your instrument’s configurations (lasers and optical filters) are appropriate for this dye.
Red 627-640 nm
695 nm
718 nm
752172 Rev.1
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Development References (4)

  1. Carel JC, Myones BL, Frazier B, Holers VM. Structural requirements for C3d,g/Epstein-Barr virus receptor (CR2/CD21) ligand binding, internalization, and viral infection. J Biol Chem. 1990; 265(21):12293-12299. (Biology). View Reference
  2. Cooper NR, Moore MD, Nemerow GR. Immunobiology of CR2, the B lymphocyte receptor for Epstein-Barr virus and the C3d complement fragment. Annu Rev Immunol. 1988; 6:85-113. (Biology). View Reference
  3. Guthridge JM, Young K, Gipson MG, et al. Epitope mapping using the X-ray crystallographic structure of complement receptor type 2 (CR2)/CD21: identification of a highly inhibitory monoclonal antibody that directly recognizes the CR2-C3d interface.. J Immunol. 2001; 167(10):5758-66. (Immunogen: Blocking, ELISA, Flow cytometry, Functional assay, Inhibition, Western blot). View Reference
  4. Szakonyi G, Guthridge JM, Li D, Young K, Holers VM, Chen XS. Structure of complement receptor 2 in complex with its C3d ligand. Science. 2001; 293(5522):1725-1728. (Biology). View Reference
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752172 Rev. 1

Please refer to Support Documents for Quality Certificates

Global - Refer to manufacturer's instructions for use and related User Manuals and Technical data sheets before using this products as described

Comparisons, where applicable, are made against older BD Technology, manual methods or are general performance claims.  Comparisons are not made against non-BD technologies, unless otherwise noted.

For Research Use Only. Not for use in diagnostic or therapeutic procedures.