title: A combination of calcium ionophore and 12-O-tetradecanoyl-phorbol-13-acetate (TPA) stimulates the growth of purified resting B cells.
abstract: In this study we investigated whether the calcium ionophores A23187 and ionomycin can act synergistically with the phorbol ester 12-O-tetradecanoyl-phorbol-13-acetate (TPA) to stimulate the growth of resting B lymphocytes purified from human tonsil cells. Ionomycin, A23187, and TPA added separately to cultures at doses of 0.4-1.6 micrograms/ml, 0.2-0.8 micrograms/ml, and 0.05-0.25 ng/ml respectively, did not induce DNA synthesis in resting B lymphocytes. In contrast, calcium ionophores at concentrations of 0.4-1.6 micrograms/ml ionomycin and 0.2-0.8 micrograms/ml A23187, in the presence of 0.05-4 ng/ml TPA, induced marked DNA synthesis and B-cell proliferation, as shown by analyses of incorporation of [3H]thymidine, growth kinetics, and the percentage of cells in the S and G2 + M phases of the cell cycle. These results show that the synergistic effects of calcium ionophores and TPA can bypass the requirement for antigen and exogenous growth factors in B-cell activation. These observations are similar to those obtained from studies of T lymphocytes by other workers.
mesh_terms: D001402:B-Lymphocytes / Q000166:cytology / Q000187:drug effects*; D000001:Calcimycin / Q000494:pharmacology*; D002453:Cell Cycle / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D004987:Ethers / Q000494:pharmacology; D006801:Humans; D015759:Ionomycin; D008213:Lymphocyte Activation / Q000187:drug effects; D010704:Phorbols / Q000494:pharmacology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*
chemical_list: D004987:Ethers; D010704:Phorbols; D000001:Calcimycin; D015759:Ionomycin; D013755:Tetradecanoylphorbol Acetate