Suppressor cells induced in the human autologous mixed lymphocyte reaction

Theophylline, a phosphodiesterase inhibitor, also reversibly inhibits the SRBC receptor of a subpopulation of human T lymphocytes. We have previously reported that the precursor for the Concanavalin A (Con A) inducible suppressor cell (SC) is found predominantly in the theophylline-sensitive (Ts) population; whereas, the precursor of the mitomycin resistant suppressor cell induced in the allogeneic mixed lymphocyte reaction (MLR) is predominantly in the theophylline-resistant (TR) subset. This study examines the theophylline sensitivity and functional characteristics of suppressor cells induced in autologous MLR (AMLR). Both TS and TR proliferate moderately in AMLR but differ in their ability to form suppressors. AMLR activated Ts and TR cells demonstrate early blastogenesis and weak suppression in the Con A assay system, but suppression in an MLR assay system appeared to be confined largely to the TR subset. AMLR suppressors were mitomycin sensitive. These data illustrate that suppressors generated in allogeneic and autologous MLR have significant functional and phenotypic similarities, and strengthen the association between these two immunologic phenomena.