Synergistic interaction between interleukin 4 and anti-Bp50 (CDw40) revealed in a novel B cell restimulation assay.
Highly purified resting B lymphocytes stimulated for 3 days to high-rate DNA synthesis by a synergistic combination of phorbol dibutyrate and ionomycin soon returned to quiescence once those signals had been removed. The maintenance of DNA synthesis in such cultures was found to provide a sensitive assay for revealing the factors that interact with cycling B cells. Whereas several activities-namely, interleukin 4, anti-Bp50 and a low molecular weight B cell growth factor-were, by themselves, capable of prolonging DNA synthesis over a further day or so, no single factor was capable of sustaining the replication cycle out to day 6 of culture. By contrast, certain combinations of activities displayed significant synergy in the restimulation assay. The most striking observed was that between interleukin 4 and anti-Bp50 where, by day 6, their combined effect on maintaining DNA synthesis in 3-day stimulated cells was the same as having kept phorbol dibutyrate and ionomycin in the culture system. The implications of these findings are discussed.
D000911:Antibodies, Monoclonal / Q000276:immunology*; D000943:Antigens, Differentiation / Q000276:immunology*; D001402:B-Lymphocytes / Q000187:drug effects / Q000276:immunology*; D004247:DNA / Q000096:biosynthesis; D004987:Ethers / Q000494:pharmacology; D006801:Humans; D015847:Interleukin-4; D007378:Interleukins / Q000494:pharmacology*; D015759:Ionomycin; D008213:Lymphocyte Activation; D015240:Phorbol 12,13-Dibutyrate; D010703:Phorbol Esters / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D000911:Antibodies, Monoclonal; D000943:Antigens, Differentiation; D004987:Ethers; D007378:Interleukins; D010703:Phorbol Esters; D015847:Interleukin-4; D015240:Phorbol 12,13-Dibutyrate; D015759:Ionomycin; D004247:DNA; D013755:Tetradecanoylphorbol Acetate