Radiosensitivity of sensitized and nonsensitized human lymphocytes evaluated in vitro.

The purpose of this study is to compare the relative radiosensitivity of sensitized and nonsensitized lymphocytes utilizing an in vitro test system. The test system employed is the combined mixed leukocyte reaction and cell-mediated lympholysis assays (MLC-CML). In this system, sensitized T lymphocytes of human origin are much more resistant to radiation-induced injury than are nonsensitized lymphocytes. The results support similar observation in vivo with antigen-activated lymphocytes and are interpreted in one of two ways: a) sensitized T cell, rendered nonviable by radiation, are still able to exert lytic activity, perhaps via the release of cytotoxic factors; and b) sensitized T cells are inherently radioresistant, perhaps due to the hypermetabolic state of such cells, which may serve to activate repair mechanisms.