Micronuclei and mitotic index in B-, T4- and T8-cells treated with mitomycin C and gamma-irradiation.

Lymphocytes were treated in vitro with mitomycin C and gamma-radiation at different doses (0-250 nmol/l and 0-2 Gy, respectively). After incubation in RPMI 1640 medium and stimulation with phytohemagglutinin for 72 h, the lymphocyte subgroups T4 (CD4), T8 (CD8) and B (CD19) were separated by an immunomagnetic method and analyzed for the presence of micronuclei. With mitomycin C the highest levels were found in T4- and B-cells. When micronuclei were induced by irradiation the T4-cells showed the highest frequencies and the B-cells the lowest. The outcome of B-cells with gamma-irradiation was probably due to a pronounced cytotoxic reaction in this cell type, which could be measured as a decrease in mitotic index.