Suppression of human T-cell mitogenesis by prostaglandin: Existence of a prostaglandin-producing suppressor cell*

Small amounts of PGE inhibit mitogen-induced [³H]thymidine incorporation in human peripheral lymphocytes. The 50% inhibitory concentration is -10^-7 M, and this is reduced to -10^-8 M when endogenous PGE production is blocked. PGE inhibits PHA- and Con A-stimulated cultures much better than PWM cultures, suggesting a differential effect of PGE on T-cell vs. B-cell function. In vitro blockade of PG synthesis results in -50% increase in [³H]thymidine incorporation in PHA cultures. PGE is produced endogenously in PHA cultures by glass adherent suppressor cells.