Human CD21 Antibody

Catalog # Availability Size / Price Qty
Detection of Human CD21 by Western Blot.
2 Images
Product Details
Citations (1)
Supplemental Products

Human CD21 Antibody Summary

Species Reactivity
Detects human CD21 in direct ELISAs and Western blots.
Monoclonal Mouse IgG1 Clone # 544408
Protein A or G purified from hybridoma culture supernatant
Chinese hamster ovary cell line CHO-derived recombinant human CD21
Accession # P20023
Lyophilized from a 0.2 μm filtered solution in PBS with Trehalose. *Small pack size (SP) is supplied either lyophilized or as a 0.2 µm filtered solution in PBS.


Recommended Concentration
Western Blot
2 µg/mL
See below
Flow Cytometry
0.25 µg/106 cells
See below
Ready to be labeled using established conjugation methods. No BSA or other carrier proteins that could interfere with conjugation.

Please Note: Optimal dilutions should be determined by each laboratory for each application. General Protocols are available in the Technical Information section on our website.

Scientific Data

Western Blot Detection of Human CD21 antibody by Western Blot. View Larger

Detection of Human CD21 by Western Blot. Western blot shows lysates of human spleen tissue. PVDF Membrane was probed with 2 µg/mL of Mouse Anti-Human CD21 Monoclonal Antibody (Catalog # MAB4909) followed by HRP-conjugated Anti-Mouse IgG Secondary Antibody (Catalog # HAF007). A specific band was detected for CD21 at approximately 145 kDa (as indicated). This experiment was conducted under non-reducing conditions and using Immunoblot Buffer Group 1. This antibody is recommended to be used under non-reducing conditions only.

Flow Cytometry Detection of CD21 antibody in Human PBMCs antibody by Flow Cytometry. View Larger

Detection of CD21 in Human PBMCs by Flow Cytometry. Human peripheral blood mononuclear cells (PBMCs) were stained with Mouse Anti-Human CD19 PE-conjugated Monoclonal Antibody (Catalog # FAB4867P) and either (A) Mouse Anti-Human CD21 Monoclonal Antibody (Catalog # MAB4909) or (B) Mouse IgG1Isotype Control (Catalog # MAB002) followed by Allophycocyanin-conjugated Anti-Mouse IgG Secondary Antibody (Catalog # F0101B).

Reconstitution Calculator

Reconstitution Calculator

The reconstitution calculator allows you to quickly calculate the volume of a reagent to reconstitute your vial. Simply enter the mass of reagent and the target concentration and the calculator will determine the rest.


Preparation and Storage

Reconstitute at 0.5 mg/mL in sterile PBS.
Reconstitution Buffer Available
Reconstitution Buffer 1 (PBS)
Catalog #
Size / Price
The product is shipped at ambient temperature. Upon receipt, store it immediately at the temperature recommended below. *Small pack size (SP) is shipped with polar packs. Upon receipt, store it immediately at -20 to -70 °C
Stability & Storage
Use a manual defrost freezer and avoid repeated freeze-thaw cycles.
  • 12 months from date of receipt, -20 to -70 °C as supplied.
  • 1 month, 2 to 8 °C under sterile conditions after reconstitution.
  • 6 months, -20 to -70 °C under sterile conditions after reconstitution.

Background: CD21

CD21 (also called EBV receptor or CR2) is a 145 kDa member of the RCA (receptors of complement activation) family of proteins. It is expressed on T cells, B cells, and follicular dendritic cells. On the B cell surface, it combines with the BCR and CD19 to form a B cell activating complex. Mature human CD21 is 1013 amino acids (aa) in length. It is a type I transmembrane (TM) protein that contains a 951 aa extracellular domain (ECD) (aa 21-971) and a short 34 aa cytoplasmic tail. The ECD exhibits fifteen 60 aa SUSHI repeats. Soluble CD21 can be generated by cleavage near the TM domain. One potential splice variant shows a deletion of aa 847‑908, while another shows an insertion of 59 aa after Lys659. The ECD of human CD21 shares 71% aa identity with mouse CD21 ECD.

Entrez Gene IDs
1380 (Human); 12902 (Mouse); 289395 (Rat)
Alternate Names
C3DR; C3DRSLEB9; CD21 antigen; CD21; Complement C3d receptor; complement component (3d/Epstein Barr virus) receptor 2; complement receptor type 2; CR2; EBV receptor; Epstein-Barr virus receptor

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Citation for Human CD21 Antibody

R&D Systems personnel manually curate a database that contains references using R&D Systems products. The data collected includes not only links to publications in PubMed, but also provides information about sample types, species, and experimental conditions.

1 Citation: Showing 1 - 1

  1. HLA-DQ ?1 alleles associated with Epstein-Barr virus (EBV) infectivity and EBV gp42 binding to cells
    Authors: Q Li, W Bu, E Gabriel, F Aguilar, Y Hoshino, H Miyadera, C Hess, RL Hornung, A Roy, JI Cohen
    JCI Insight, 2017-02-23;2(4):e85687.
    Species: Human
    Sample Types: Whole Cells
    Applications: Flow Cytometry


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Isotype Controls

Reconstitution Buffers

Secondary Antibodies

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