特異性：CD19 B cell differentiation antigen, Mr 95 kDa CD19 is a monomeric transmembrane glycoprotein expressed at relatively constant levels throughout B cell development from early pro-B/pre-B cells (i.e., B220^+/CD43^+/HSA^+) through fully differentiated B cell stages. ^1-7 Terminally differentiated plasma cells do not express CD19. ^1 In humans, the CD19 molecule on the surface of mature B cells associates with CD21 (CR-2) and CD81 (TAPA-1), and this multimolecular complex synergizes with surface immunoglobulin to provide signal transduction and promote cellular activation. ^3, 4 All splenic and peritoneal IgM^+ cells of both B-1 and B-2 lineages are CD19^+, with B-1 cells expressing higher levels of CD19 than B-2 cells in these sites. ^1, 7 Recent studies with CD19-deficient mice have suggested that this molecule may not be required for normal generation and maturation of B cells in the bone marrow. ^7
