Suppressor T-cell activity in newborns and mothers.

We studied autologous and allogeneic concanavalin A (Con A)-induced suppression of proliferative responses to phytohemagglutinin (PHA) and Con A in peripheral blood mononuclear cells in 24 normal newborns and compared the results with those obtained from 20 normal older children. Three concentrations of PHA and one of Con A were used to stimulate responder cells. Suppressor activity, elicited in the stimulated cell population after 48 h pre-incubation with Con A, was expressed as percentage inhibition of the proliferative response to PHA. There was an inverse relationship between PHA concentration and suppressor activity, and autologous suppression was greater than allogeneic suppression within each group of patients and at each mitogen concentration. In both the autologous and allogeneic systems, older children showed more suppressor activity than newborns. Feto-maternal pairing showed that newborns efficiently suppress their mother's mitogenic responses, but the mothers do not suppress their own or other newborn's lymphocytes, despite having normal autologous suppressor capability. We suggest that suppressor activity by the fetus and it's inhibition in the mother may play a part in the mechanism for controlling maternal-fetal immune rejection.