Natural killer and tumor recognizing lymphocyte activity in tumor patients

Several mechanisms can lead to the killing of a target cell by lymphocytes. In order to study immunologically specific phenomena it has to be ensured that the natural killer (NK) effect does not operate in the system. Using targets which are sensitive to NK, the effector populations have to be depleted of lymphocytes with such potential. The blood lymphocytes of tumor carrying patients often have reduced NK activity. In two assay systems anti-tumor autoimmune reactivity has been demonstrated (the majority of tested patients had lung carcinomas or osteosarcomas). The tests were: 1. Induction of blastogenesis in blood lymphocytes by in vitro confrontation with autologous biopsy cells. 2. Lymphocyte mediated killing of autologous biopsy cells in short term in vitro assay. Cross reactivity between patients was rare which indicates either that the putative tumor antigens are individual specific or their recognition is restricted by histocompatibility.