CD45.1 Antibody [A20] (FITC)

The CD45 antigen is an essential regulator of leukocyte activation and development and is now known to be a protein tyrosine phosphatase, e.g., CD45 is able to dephosphorylate the Src family of protein kinases. This activity is now known to be required for signal transduction induced by T and B cell antigen receptor engagement, cytokine signaling, and Fc receptor stimulation. The functional state of CD45 also has a pronounced effect on lymphocyte development. CD45 exists in multiple forms, such as the restricted variants (CD45R; see companion products 1660, 1665, 1675, 1685, and 1820) and as allelic forms CD45.1 (Ly-5.1) and CD45.2 (Ly-5.2) . The former arises as a result of alternative splicing of different exons. The specificity of antibodies to CD45.1 and CD45.2 has been exploited in studies where resolution of donor and recipient cells is essential, such as in gene therapy or bone marrow transplantation. The monoclonal antibody A20 recognizes all mouse leukocytes expressing the CD45.1 allotype.