THE EFFECT OF RADIATION-THERAPY ON IMMUNE FUNCTION IN PATIENTS WITH SQUAMOUS-CELL LUNG-CARCINOMA

The immune response is impaired in patients with malignancy, and radia tion therapy (RT) can exacerbate the cancer induced-attenuation of imm une response. In order to search for the fine mechanisms behind the RT -induced attenuation of cell-mediated immune response, we measured the number of lymphocytes in peripheral blood, its subsets, and lymphobla st transformation induced by phytohemagglutinin (PHA), purified protei n derivatives (PPD), mitogenic monoclonal antibody anti-CD3, and mitog enic combination of anti-CD2 antibodies 9-1 and 9.6 before and after R T in 19 patients with squamous cell lung cancer. Radiation therapy sig nificantly decreased the total numbers of lymphocytes, CD-3, CD-4, and CD8-positive lymphocytes in peripheral blood However, RT did not chan ge the per centages of lymphocytes and its subsets. Radiation therapy increased the percentage of interleukin 2 (IL-2) receptor-positive lym phocytes, and RT significantly decreased in vitro lymphoblast transfor mation by PHA, PPD, or monoclonal antibodies to T-cell surface antigen s (anti-CD2 or anti-CD3). In vitro incubation with IL-2 did not increa se lymphoblast transformation by anti-CD3 before RT but significantly increased after RT. In conclusion, we suggest that one of the fine mec hanisms behind the RT-induced suppression of immune responsiveness of patients with lung cancer is a defect in IL-2 synthesis by lymphocytes .