Mouse Monoclonal. Intended for in vitro diagnostic (IVD) use. This antibody reacts with CD21 antigen of MW 145 kDa, present on the surface of mature B cells. The antigen is present at high density on follicular dendritic cells. CD21 is involved in transmitting growth-promoting signals to the interior of the B cell. References 1. Petzer et al. Immunology 63: 47, 1988. 2. Weis et al. Proc Natl Acad Sci USA 81: 881, 1984. 3. Nemerow et al. J Immunol 135: 3068, 1985.