BSF-1 action on resting B cells does not require elevation of inositol phospholipid metabolism or increased [Ca2+]i.
B cell stimulatory factor-1 (BSF-1) acts on resting B cells to increase expression of class II major histocompatibility complex (MHC) molecules and to prepare for more prompt entry into S phase in response to anti-IgM and lipopolysaccharide. It also acts as a costimulant, with low concentrations of anti-IgM, to cause resting B cells to synthesize DNA. Unlike anti-IgM, BSF-1 does not cause elevation in inositol phospholipid metabolism or in concentration of intracellular free calcium, nor does it enhance such biochemical responses to anti-IgM. Furthermore, increased expression of class II MHC molecules to BSF-1 is observed when essentially all extracellular calcium is chelated by EGTA, whereas lower concentrations of EGTA completely inhibit increases in class II molecules in response to anti-IgM. These results indicate that BSF-1 effects on resting B cells are not mediated by the inositol phospholipid metabolic pathway.
D000818:Animals; D000888:Antibodies, Anti-Idiotypic; D001402:B-Lymphocytes / Q000276:immunology / Q000502:physiology*; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000502:physiology*; D004261:DNA Replication / Q000187:drug effects; D005260:Female; D006133:Growth Substances / Q000494:pharmacology*; D000949:Histocompatibility Antigens Class II / Q000276:immunology; D015847:Interleukin-4; D007399:Interphase; D008222:Lymphokines / Q000494:pharmacology*; D051379:Mice; D008807:Mice, Inbred BALB C; D010716:Phosphatidylinositols / Q000378:metabolism*; D011947:Receptors, Antigen, B-Cell / Q000276:immunology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D000888:Antibodies, Anti-Idiotypic; D006133:Growth Substances; D000949:Histocompatibility Antigens Class II; D008222:Lymphokines; D010716:Phosphatidylinositols; D011947:Receptors, Antigen, B-Cell; D015847:Interleukin-4; D000001:Calcimycin; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium