Age and dose related alteration of in vitro mixed lymphocyte culture response of blood lymphocytes from A-bomb survivors.

The responsiveness of peripheral blood lymphocytes to allogenic antigens in mixed lymphocyte culture (MLC) was measured in 139 atomic-bomb survivors. The study revealed a significant decrease in MLC response with increasing dose of previous radiation exposure. This decline was marked in the survivors who were older than 15 at the time of the bomb (ATB). The results suggest a possible relationship between the recovery of T-cell-related function and the thymic function which processes mature T cells for the immune system. Thus it may be that in the advanced age ATB group, the thymus function had started to involute, allowing less recovery of T-cell function compared to young survivors who had adequate processing T-cell activity.