Reference Database

B-cell stimulatory factor-I (BSF-I) is a 20,000-Mr protein produced by some activated T cells. First described as a costimulant of the entry into S-phase of resting mouse B cells incubated with anti-immunoglobulin (Ig) antibodies (1), BSF-I has now been shown to act on resting B cells to increase their expression of class-II major histocompatibility complex (MHC) molecules (2, 3) and to increase markedly the production of IgG I (4-6) and IgE (7) by B-cell populations stimulated with lipopolysaccharide (LPS). Although initially believed to be principally active on B cells, BSF- 1 has been shown to increase the viability and to stimulate growth of normal T cells (8, 9) and of certain T -cell lines (10-13), to act as a costimulant for growth of some mast cell lines ( 1 0, 14), and to act on several other hematopoietic lineage cells (15,16), including granulocyte, megakaryocyte, and erythroid precursors and macrophages. It has been proposed that BSF-I be designated interleukin-4 (IL-4) (17). Because of the likelihood that there are a large number of distinct lymphocyte products for which an interleukin designation may soon be sought, the nonspecialist may find it increasingly difficult to associate an interleukin name with the functions of a particular molecule. For that reason, we prefer to use the historic or "trivial" name of the lymphokine, but in association with an interleukin designation, to avoid any possible confusion. Thus, at the beginning of any discussion of a paper in which BSF-I is used, we refer to it as BSF-I/IL-4 and thereafter, as BSF-I.