CD21

CD21, also known as CR2, complement component (3d/Epstein Barr virus) receptor 2, is an integral membrane glycoprotein of molecular weight 140 kDa, involved in the complement system. CD21 binds to C3d. B-cells have CR2 receptors on their surfaces, allowing the complement system to play a role in B-cell activation and maturation. Complement component receptor-2 (CR2) is the membrane protein on B-lymphocytes to which the Epstein-Barr virus (EBV) binds during infection of these cells.

Anti-CD21 is useful in the identification of follicular dendritic cell matrixes found in normal lymph nodes and tonsillar tissue. This antibody also labels Follicular Dendritic Cell Tumor/Sarcomas. The antigen is absent on T-lymphocytes, monocytes, and granulocytes.

CD21 is a rabbit monoclonal antibody derived from cell culture supernatant that is concentrated, dialyzed, filter sterilized and diluted in buffer pH 7.5, containing BSA and sodium azide as a preservative.

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1. Cut and mount 3-4 micron formalin-fixed paraffin-embedded tissues on positive charged slides.
2. Air dry for 2 hours at 58° C.
3. Deparaffinize, dehydrate and rehydrate tissues.
4. Subject tissues to heat epitope retrieval using a suitable retrieval solution such as ImmunoDNA Retriever with Citrate (BSB 0020-BSB 0023) or EDTA (BSB 0030-BSB 0033).
5. Any of three heating methods may be used:
   • Electric Pressure Cooker
     Place standoff rack at base of pressure cooker. Add 1-2 inches of distilled water to the pressure cooker and turn heat to high, and incubate for 15 minutes. Open and immediately transfer slides to room temperature.
   • Water Bath Method
     Place tissues/slides in a pre-warmed staining dish or coplin jar containing the ImmunoDNA Retriever with Citrate or EDTA in a water bath set at 95°-99° C. Incubate for 30-60 minutes.
   • Conventional Steamer Method
     Place tissues/slides in a pre-warmed staining dish or coplin jar containing the ImmunoDNA Retriever with Citrate or EDTA in a Steamer, cover and steam for 30-60 minutes.
6. After heat treatment, transfer slides in ImmunoDNA Retriever with Citrate or EDTA to room temperature and let stand for 15-20 minutes.
7. Wash slides with IHC wash buffer or DI water.
8. Continue IHC staining protocol.