Radioadaptive response in human B- and CD8+ T-lymphocytes as measured by the acridine orange stained micronuclei technique

To investigate (1) the radiosensitive of B- versus T- lymphocytes and (2) the possible application of their sensitivity for adaptive response after treating with an adapting plus a challenge dose. In the present experiments, micronucleus analysis was performed in B- and CD8+ matured T-lymphocytes of eight healthy volunteers exposed to γ-rays. The number of radio-induced micronuclei was significantly higher in B-lymphocytes compared to T-lymphocytes in the dose range from 10 to 100cGy. To investigate adaptive response, whole blood samples were irradiated in vitro with a pretreatment dose of 1cGy 137Cs γ-irradiation. Six hours after their initiation, groups of cultures were subsequently exposed to a challenge dose of 100cGy γ-irradiation. Following stimulation with PHA and PWM for T- and B-lymphocyte cultivation, lymphocytes were fixed at 72 hours and stained with acridine orange dye. B-lymphocytes exhibited a greater induction of adaptive response than those of CD8+ matured T-lymphocytes, and when pretreated with 1cGy significantly fewer micronuclei induced by the challenge dose of 100cGy γ-irradiation. The results suggest that the lower dose pretreatments are able to induce a significantly higher adaptive response in human B-lymphocytes, and this adaptive response may result from the DNA repair mechanism, which may lead to less residual damage. (author)