CD21 Recombinant Monoclonal Antibody

Code CSB-RA005934A0HU
Size US$210
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  • Western Blot
    Positive WB detected in Raji whole cell lysate
    All lanes CD21 antibody at 0.55μg/ml
    Goat polyclonal to rabbit IgG at 1/50000 dilution
    Predicted band size: 155 KDa
    Observed band size: 155 KDa
  • IHC image of CY5710 diluted at 1:100 and staining in paraffin-embedded human tonsil tissue performed on a Leica BondTM system. After dewaxing and hydration, antigen retrieval was mediated by high pressure in a citrate buffer (pH 6.0). Section was blocked with 10% normal goat serum 30min at RT. Then primary antibody (1% BSA) was incubated at 4℃ overnight. The primary is detected by a biotinylated secondary antibody and visualized using an HRP conjugated SP system.
  • IHC image of CSB-RA005934A0HU diluted at 1:100 and staining in paraffin-embedded human lung cancer performed on a Leica BondTM system. After dewaxing and hydration, antigen retrieval was mediated by high pressure in a citrate buffer (pH 6.0). Section was blocked with 10% normal goat serum 30min at RT. Then primary antibody (1% BSA) was incubated at 4℃ overnight. The primary is detected by a biotinylated secondary antibody and visualized using an HRP conjugated SP system.
  • Immunofluorescence staining of Raji cells with CSB-RA005934A0HU at 1:34,counter-stained with DAPI. The cells were fixed in 4% formaldehyde, permeabilized using 0.2% Triton X-100 and blocked in 10% normal Goat Serum. The cells were then incubated with the antibody overnight at 4℃.The secondary antibody was Alexa Fluor 488-congugated AffiniPure Goat Anti-Rabbit IgG (H+L).
  • Overlay histogram showing Raji cells stained with CSB-RA005934A0HU (red line) at 1:50. The cells were fixed with 70% Ethylalcohol (18h) and then permeabilized with 0.3% Triton X-100 for 2 min.The cells were then incubated in 1x PBS /10% normal goat serum to block non-specific protein-protein interactions followed by primary antibody for 1 h at 4℃.The secondary antibody used was FITC goat anti-rabbit IgG (H+L) at 1/200 dilution for 1 h at 4℃. Control antibody (green line) was used under the same conditions. Acquisition of >10,000 events was performed.

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Product Details

Uniprot No.
Target Names
Alternative Names
C3DR antibody; CD 21 antibody; CD21 antibody; Complement C3d receptor 2 antibody; Complement C3d receptor antibody; Complement component (3d/Epstein Barr virus) receptor 2 antibody; Complement receptor type 2 antibody; CR antibody; Cr2 antibody; CR2_HUMAN antibody; CVID7 antibody; EBV receptor antibody; EBV-R antibody; Epstein Barr virus receptor antibody; Epstein-Barr virus receptor antibody; EVBR antibody; SLEB9 antibody
Species Reactivity
A synthesized peptide
Immunogen Species
Homo sapiens (Human)
Rabbit IgG
Clone No.
Purification Method
It differs from different batches. Please contact us to confirm it.
Rabbit IgG in phosphate buffered saline, pH 7.4, 150mM NaCl, 0.02% sodium azide and 50% glycerol.
Tested Applications
Recommended Dilution
Application Recommended Dilution
WB 1:500-1:5000
IHC 1:50-1:500
IF 1:30-1:200
Troubleshooting and FAQs
Upon receipt, store at -20°C or -80°C. Avoid repeated freeze.
Lead Time
Basically, we can dispatch the products out in 1-3 working days after receiving your orders. Delivery time maybe differs from different purchasing way or location, please kindly consult your local distributors for specific delivery time.

The DNA sequence coding for the CD21 monoclonal antibody developed from animals immunized with a human CD21 synthetic peptide was cloned into an expression vector and then transfected into a cell line for in vitro expression. The recombinant CD21 monoclonal antibody was obtained through affinity chromatography purification of the product from the tissue culture supernatant (TCS). The human CD21 is especially targeted by this CD21 antibody. It's a rabbit IgG antibody. This CD21 antibody has been evaluated using ELISA, WB, IHC, IF, and FC methods.

CD21, also termed CR2, binds to a number of endogenous ligands, including the complement component C3 fragments iC3b, C3dg, and C3d, the low-affinity IgE receptor CD23, and interferon-alpha. By binding to C3d, which is covalently linked to targets, CR2 connects the innate complement-mediated immune response to pathogens and foreign antigens with the adaptive immune response, leading to a cell signaling event that lowers the threshold for B cell activation. A range of autoimmune and inflammatory disorders are linked to mutations or deletions of the CR2 gene in humans and the CR2 gene in mice.

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Target Background

Receptor for complement C3, for the Epstein-Barr virus on human B-cells and T-cells and for HNRNPU. Participates in B lymphocytes activation.; (Microbial infection) Acts as a receptor for Epstein-Barr virus.
Gene References into Functions
  1. This study shown the C3d+ microglial clusters were found in chronic but not acute multiple sclerosis. PMID: 27778395
  2. This study uncovers the origin of the effect of ionic strength on C3d-CR2 interaction and deepens the understanding of the molecular mechanism of their interaction, which is valuable for the design of vaccines and small molecule inhibitors. PMID: 27154286
  3. Binding of PF4/heparin complexes to B cells is mediated through the interaction between complement and complement receptor 2. PMID: 27412887
  4. high pERK expression and accelerated apoptosis revert within 4 weeks after beginning therapy, whereas clonal B cells unresponsive to TLR9 stimulation persist for at least 24 weeks, although they may partially rescue normal CD21 expression. PMID: 28507081
  5. Cerebrospinal fluid (CSF) soluble complement receptor 2 (sCR2) levels correlated significantly both with CSF complements C3 and C1q as well as to a disease severity measure. PMID: 27085202
  6. CR2 contributes to human Osteonecrosis of the femoral head susceptibility in Korean systemic lupus erythematosus patients. PMID: 27446959
  7. In this study, we have shown that the CR2 +24T>C polymorphism is not a risk marker for nasopharyngeal carcinoma development in the North region of Portugal. PMID: 26748973
  8. In mature B cells, CD21 transcription proceeds from a focused transcriptional start site regulated by a non-consensus TATA box, an initiator element and a downstream promoter element. PMID: 25640655
  9. Reduced expression of CD21 on CLL B-cells appears functionally relevant and was associated with poor clinical outcomes. PMID: 26452134
  10. These data suggest that rs1876453 in CR2 has long-range effects on gene regulation that decrease susceptibility to systemic lupus erythematosus. PMID: 25180293
  11. repression of the CR2/CD21 promoter can occur through one of the E-box motifs via recruitment of RP58. PMID: 25817480
  12. found that the protective CR2 genotype is correlated with lower levels CR2 mRNA as well as differences in the ratio of the long and short CR2 isoforms PMID: 25569262
  13. The paradoxical enhancement of immune responses by C3d in the absence of CD21 is due to internalization and processing of C3d into peptides that activate autoreactive CD4(+) T-helper cells. PMID: 25385064
  14. Higher C3d/C3 ratios were found for current smoker, higher age, age-related macular degeneration phenotype, and the two SNPs in the C3 gene, rs6795735 and rs2230199. PMID: 24675670
  15. Authors show that expression of the Epstein-Barr virus B-cell attachment receptor, CD21, in B cells that lack this receptor results in significant changes in gene expression, both before and rapidly following EBV-CD21 interaction. PMID: 24600013
  16. Our findings implicate CR2 as a susceptibility gene for nasopharyngeal carcinoma and suggest that enhanced CR2 expression may be involved in the oncogenesis and development of nasopharyngeal carcinoma. PMID: 23612877
  17. To eradicate this virus, targeting CD21 on these EBV-infected B cells is hypothesized here. PMID: 23384704
  18. Patients with primary Sjogren's Syndrome who display high frequencies of autoreactive and unresponsive CD21-/low B cells are susceptible to developing lymphoproliferation. PMID: 23279883
  19. plasma sCD21 levels are higher, while B-cell surface CD21 expression levels are lower in B-cell chronic lymphocytic leukemia (B-CLL) patients, but not in multiple myeloma (MM) patients. PMID: 22899340
  20. Transgenic mice inoculated with elk brain homogenate expressing high levels of prion (PrPC) protein die of chronic wasting disease. PMID: 23002439
  21. All subtypes of juvenile arthritis have reduced circulating levels of sCD21 and sCD23. PMID: 21328056
  22. These results suggest that CR2 plays a role in the recognition of foreign DNA during host-immune responses PMID: 22885687
  23. the 5' UTR is a novel regulatory element for the CR2 gene in which variation may alter gene function and modify the development of Systemic lupus erythematosus PMID: 22673213
  24. Prevalence of pulmonary fibrosis in patients with diffuse cutaneous systemic sclerosis inversely correlates with soluble cluster of differentiation 21 (sCD21) levels. PMID: 21052675
  25. Marginal zone B cells activated by hepatitis C virus undergo functional exhaustion associated with BCR signaling defects and overexpression of a key antiproliferative gene, and may subsequently become terminally spent CD21(low) B cells. PMID: 22678901
  26. CD21 expression is altered in multiple sclerosis (MS) patients as in other autoimmune diseases, although no evidence is found for a specific role of the CD21 gene in MS. PMID: 22137275
  27. Patients with hepatitis C virus infection who display high frequencies of unresponsive CD21(-/low) marginal zone B cells are more susceptible to developing autoimmunity and/or lymphoproliferation. PMID: 22084433
  28. CD23 oligomers appear more important in enhancing IgE synthesis and monomers lacking the tail residues fail to bind CD21 yet bind membrane IgE and down-regulate IgE synthesis. PMID: 21889131
  29. study reports a cocrystal structure of a CR2(SCR1-2):C3d complex at 3.2 angstrom resolution in which the interaction interfaces differ markedly from the previously published structure and are consistent with the biochemical data PMID: 21527715
  30. The impact of hCR2 expression on mouse B cell development and the baseline immunological status of the mice, was evaluated. PMID: 21269698
  31. Binding between Epstein Barr virus-transformed B cell line-derived exosomes and viral structural protein gp350 is dependent on CD21 expressed on the B cells. PMID: 21106852
  32. Molecular modeling approaches used to investigate disparities between the biochemical data and the X-ray structure of the CR2-C3d cocrystal result in highest-scoring solutions in which CR2 SCR1-2 is docked within the concave surface of C3d. PMID: 20951140
  33. Biophysical investigations of complement receptor 2 (CD21 and CR2)-ligand interactions reveal amino acid contacts unique to each receptor-ligand pair PMID: 20558730
  34. analysis of the physicochemical properties underlying C3d-CR2 association PMID: 20091675
  35. Staphylococcus aureus binder of Ig (Sbi) and complement receptor 2 (CR2) share overlapping binding sites on complement 3d (C3d), thus allowing the bacterial evasion molecule to block CR2 binding, thereby inhibiting the host's adaptive immune response. PMID: 20083651
  36. CR2-induced complement activation results in membrane depolarization, as indicated by annexin V binding, with kinetics similar to those of C3-fragment deposition and different from those of membrane attack complex formation. PMID: 19740327
  37. promoter activity is critically dependent on a cell type-specific repressor PMID: 11739509
  38. Redox control of EBV infection: prevention by thiol-dependent modulation of functional CD21/EBV receptor expression. PMID: 11813981
  39. crystal structure of human CD21; implications for epstein-barr virus and c3d binding PMID: 12122212
  40. The percentage of T cells expressing CD21 from all gestations was significantly higher than the adult and the percentage positive decreased with increasing gestational age. PMID: 12149502
  41. NF-kappaB signaling pathway enhances the expression of the CR2 gene, as a result of NF-kappaB proteins binding to two CR2 promoter elements. PMID: 12444129
  42. CR2 is shed mainly as a soluble CR2 complex, in which the CR2 units link covalently and react with nucleophilic agents PMID: 12713795
  43. Complement receptor 2-mediated targeting of complement inhibitors to sites of complement activation. PMID: 12813023
  44. Coligation of CD21 with the B cell antigen receptor lowers the antigen concentration threshold for eliciting protection from Fas apoptosis by 2-3 orders of magnitude. PMID: 14607925
  45. electrostatic calculations provide global and site-specific explanations of the physical causes that underlie the ionic strength dependence of C3d-CR2 association PMID: 15187133
  46. The activation of MAPKs is independently mediated by CR2 and that anti-CR2 McAb, PD98059, and Wortmanin block the activation of MAPKs, respectively. PMID: 15603708
  47. characterized the interaction between the first two short consensus repeats (SCR1-2) of complement receptor type 2 (CR2, CD21) and C3d PMID: 15713467
  48. the open V-shaped structures formed by CR2 SCR 1-2, both when free and when bound to C3d, are optimal for the formation of a tight two-domain interaction with its ligand C3d PMID: 15713468
  49. CD21 and CD23a are common targets for B lymphotropic gammaherpesviruses. PMID: 15795251
  50. Unresponsiveness to T-dependent antigen (sheep red blood cells) displayed by transgenic CR2-positive B cells is linked to increase in the stimulus level required to propel the B cell into a fully activated state, a normal humoral immune response. PMID: 15905540

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Involvement in disease
Systemic lupus erythematosus 9 (SLEB9); Immunodeficiency, common variable, 7 (CVID7)
Subcellular Location
Cell membrane; Single-pass type I membrane protein.
Protein Families
Receptors of complement activation (RCA) family
Tissue Specificity
Mature B-lymphocytes, T-lymphocytes, pharyngeal epithelial cells, astrocytes and follicular dendritic cells of the spleen.
Database Links

HGNC: 2336

OMIM: 120650

KEGG: hsa:1380

UniGene: Hs.445757

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