Partial characterization of a prostaglandin-induced suppressor factor

Glass adherent splenic T cells, cultured in the presence of prostaglandin E₂ (10^?5M), were found to elicit a factor capable of nonspecifically suppressing PHA- and LPS-induced mitogenesis. Cells from C57B1/6J, Balb/C, and C3H/He mice were all capable of producing this suppressor factor, although some degree of variability in the response of cells from C3H mice to the factor was observed. The suppressor (designated prostaglandin-induced T-cell derived suppressor, PITS) was characterized biochemically and it was found that the activity was resistant to boiling, and treatment with RNase and DNase, yet was sensitive to treatment with proteinase K, trypsin, and Pronase. Further, PITS supernatants were found to contain at least two suppressors with approximate molecular weights of 35,000 (PITS_α) and 5000 (PITS_β). Results from experiments with cycloheximide-treated glass-adherent T cells indicate that prostaglandin E₂ may function by inducing the release rather than de novo synthesis of the PITS. These results indicate that the reported overall suppressive effect of prostaglandin E₂ on lymphocytes may in part be due to the release by certain T cells of a suppressive factor.