CD20, also known as membrane-spanning 4-domains subfamily A member 1 (MS4A1), was the first B cell differentiation antigen identified. CD20 is highly expressed by B cell lymphocytes throughout their development, but is absent on the hematopoietic stem cells []. Anti-CDC20 antibodies are commonly used for the treatment of B-cell lymphoid malignancies [].The function of CD20 remains unclear. It may be involved in calcium signalling downstream of B cell antigen receptor activation [, ]. CD20 has a been shown to play a central role in the generation of T cell-independent antibody responses [].
