The effect of in vitro irradiation on PHA-mediated cytotoxicity and lymphocytes with receptors for the Fc part of Ig.

In vitro irradiation of purified human lymphocytes reduced PHA-mediated cytotoxicity (MICC) against chicken erythrocytes in a dose-dependent fashion. Lymphocytes with receptors for IgG present in both unfractionated and T-cell enriched cell preparations were depleted after X-ray exposure. T-cells with IgM-receptors, however, appeared to be more resistant. Different lymphocyte subpopulations seem to cooperate in MICC, and shifts of their proportions may be one explanation of the reduction of MICC after X-ray exposure.