CD45.1 Mouse anti-Mouse, FITC, Clone: A20, BD

The A20 monoclonal antibody specifically binds to CD45 (Leukocyte Common Antigen) on all leukocytes of mouse strains expressing the CD45.1 alloantigen (eg, RIII, SJL/J, STS/A, DA). This alloantigen was originally named Ly-5.2, and this was the designation at the time that the antibody was characterized. The designation was later changed from Ly-5.2 to Ly-5.1 to conform with the convention that the .2 alloantigen designations be assigned to the C57BL/6 strain. mAb A20 has been reported not to react with leukocytes of most other mouse strains, which express the CD45.2 alloantigen. CD45 is a member of the Protein Tyrosine Phosphatase (PTP) family: Its intracellular (COOH-terminal) region contains two PTP catalytic domains, and the extracellular region is highly variable due to alternative splicing of exons 4, 5, and 6 (designated A, B, and C,respectively), plus differing levels of glycosylation. The CD45 isoforms detected in the mouse are cell type-, maturation-, and activation state-specific. The CD45 isoforms play complex roles in T-cell and B-cell antigen receptor signal transduction. The A20 antibody has been reported to inhibit some responses of B cells, from mice expressing the CD45.1 alloantigen, to antigens and LPS.