Plaque-Forming Cells in Man

The influence of acetylsalicylic acid (ASA) and steroid (ST) on the number of plaque-forming cells (PFC) developed in pokeweed mitogen-activated cultures of peripheral blood lymphocytes (PBL) was investigated. Cultures of 10(6) PBL were established from blood samples of 16 healthy volunteers before and after intake of 2 g of ASA, and parallel cultures were supplemented with ST in vitro. The immunoglobulin secretion was monitored with a protein A assay. Our results show that pharmacological doses of ASA in vivo decrease the number of PFC by 41%, whereas the distribution of the subpopulations was unaltered. In cultures of PBL obtained before the intake of ASA and supplemented with 10, 50 or 100 micrograms/ml of dexamethasone the number of PFC was decreased by 50%, 41% and 44%, respectively. In cultures of PBL obtained after the intake of ASA and supplemented with 10, 50 or 100 micrograms of ST, the number of PFC was further decreased by 22%, 32% and 38%. The effects of ASA in vivo and ST in vitro were additive. The ratio of IgM, IgG and IgA PFC was unaffected by ASA and ST. It is suggested that the modulation of the PFC response induced by ASA and ST is mediated by the prostaglandin system.