The acute effects of ionizing radiation on DNA synthesis and the development of antibody-producing cells.

Ionizing radiation inhibited the development of specific haemolysin-producing cells (PFC) and depressed the incorporation of (3H) thymidine by rabbit spleen explants responding to SRC in the culture medium. In contrast to these effects, the rates of incorporation of precursors for protein and RNA synthesis were much less affected. The depression of (3H) thymidine incorporation was found to result from a quantitative reduction of new DNA synthesis, without any change in the proportion of labelled cells, at any time after irradiation. The DNA synthesis occurring in these cells preparing to develop antibody-producing capacity was thus radio-sensitive, but the exact nature of the defect resulting from exposure to radiation requires further study.