Delineation of human B cell differentiation: immunological and molecular characterization of human B cell differentiation factor (BSF-2).

Abstract

B cells, which are responsible for the secretion of antibodies, originate from pluripotent hematopoietic stem cells and differentiation stages, such as pre-B cells, mature B cells, activated B cells and antibody secreting cells. The commitment of each B cell clone to a specific antigen occurs at the pre-B cell level and mature B cells express IgM molecules as antigen receptors on their surface. Binding of an antigen complementary to the receptors of a certain B cell clone initiates a complex series of the activation process resulting into antibody secreting cells. This process of clonal expansion and differentiation requires the collaboration of helper T cells. Recently, the T cell-dependent activation process of B cells into antibody secreting cells has been extensively studied and the involvement of B cell specific growth and differentiation factors in this process has been demonstrated (1,2). The results are schematically summarized in Fig. 1.