Induction of suppressor activity in the autologous mixed lymphocyte reaction and in cultures with concanavalin A.

T lymphocytes that are activated in the autologous mixed lymphocyte reaction (MLR) have suppressor activity. Concanavalin A (Con A) augments the suppressor activity generated in cultures containing both T and non-T lymphocytes and can induce suppressor activity in T-lymphocyte preparations that contain too few (10%) non-T cells to generate a significant autologous MLR. However, when such T-lymphocyte preparations are further depleted of adherent cells and contain less than 2% non-T cells, Con A fails to induce suppressor activity. These findings support the concept that an autologous MLR may play an important role in generation of suppressor cells by Con A.