Experimental and clinical data for the role of NK-cells in immunosurveillance.

Blood lymphocyte subsets separated on the basis of densities from 14 healthy donors and 25 patients with solid tumors were tested for lytic effect against allogeneic or autologous tumor cells derived from surgical specimens. The allogeneic combinations comprised 36 tests on 28 tumors. In these the total lymphocyte population was cytotoxic in one experiment. On the other hand, 16 experiments with density separated subsets were positive. The lytic effect resided in the light subset. Auto-tumor lysis excreted by total lymphocyte population occurred in 7 of 25 cases. Additional 11 tests showed cytotoxicity with the separated subsets. The autologous tumor cells were damaged by the light lymphocytes of 15 patients. Among these 6 had cytotoxic cells also in the high density subset. In seven cases auto-tumor lysis was exerted only by the dense lymphocytes. Thus in 13 cases the profile of auto tumor lysis differed from that observed with the allogeneic combinations and against K562. The autologous system may represent an immune situation and therefore it may not be unexpected that a proportion of the active cells have different phenotypic characteristics compared to the operationally natural killer system.