Clone REA940 recognizes the human CD21 antigen, a type I membrane glycoprotein. Expression of CD21 in humans is found on B cells, follicular dendritic cells, subsets of epithelial cells, and thymic T cells. The primary function attributed to CD21 has been to amplify the B cell receptor (BCR)–mediated signal transduction in response to antigen recognition. To enhance the BCR mediated activation, CD21 associates with CD19 and CD81 in a B cell–specific signal transduction complex, where interaction of BCR with CR2/CD19 amplifies the signals. In addition, CD21 serves as a receptor for split products of complement protein C3, the gp350/220 viral coat protein of the EBV and the immunoregulatory protein CD23.
Additional information: Clone REA940 displays negligible binding to Fc receptors.