Suppressor T cells (Ts) may play an important role in the regulation of immunological responses. Ts may play a role in the long-term acceptance of an allogeneic organ graft and the beneficial effects of donor-specific blood transfusions on subsequent transplant survival. The population of Ts induced in mixed lymphocyte culture (MLC) was analyzed, and the mechanism underlying the suppressor activity was examined. The Ts generated in 10-day MLC were found to belong to the OKT8(+) subset and inhibited both mixed lymphocyte reaction (MLR) and cell-mediated lympholysis. These Ts inhibited MLR in an antigen-specific manner, but failed to alter the kinetics of the MLR. Furthermore, these Ts inhibited the production of endogenous interleukin-2 and exerted a suppressive effect only when added early in the culture. In condition, the precise target of Ts generated in 10-day MLC might be the earliest responding T helper clone.
mixed lymphocyte reaction