Radiosensitive suppressor T cells for LIF production in mixed lymphocyte reactions

LIF activity in the supernatants of one way MLR, one MNC population being irradiated, was significantly increased as compared to that produced in two way MLR. Puromycin treatment of the irradiated cells decreased LIF response while puromycin treatment of the non-irradiated cells had no detectable effect. A similar increase of LIF activity was achieved by removing either OKT8+ or OKT4+ cells from one cell component before performing the mixed culture. Recombination of the depleted cell samples followed by MLR decreased LIF response except when belonging to allogeneic donors. Mostly, irradiation of OKT8 depleted mononuclear cells before recombination with OKT4 depleted cells prevented LIF suppression in MLR. The suppressor function of OKT4+ cells seems to be more radiosensitive than that of OKT8+ cells in this system. It is suggested that LIF production in MLR is regulated by a suppressor circuit which is histocompatible restricted and requires interaction of both OKT4+ and OKT8+ cells.