SUPPRESSOR CELL-ACTIVITY OF LYMPHOCYTES INFILTRATING HUMAN-LUNG AND BREAST-TUMORS

Tumour‐infiltrating lymphocytes (TIL) can be isolated from human lung and breast tumours by the stepwise application of velocity and density sedimentations on discontinuous Ficoll‐Triosil or bovine serum gradients. The populations obtained showed variable composition with respect to lymphocyte subsets but generally corresponded to that of peripheral blood lymphocytes (PBL) containing primarily T cells (mean, 49% E rosettes; 15% EA rosettes). Comparison of reactivity to PHA in 15 individuals revealed a significant deficit in reactivity in the TIL population compared with blood and lymph‐node lymphocytes. TIL showed no natural killer (NK) activity, no response to autologous tumour in mixed lymphocyte target interaction tests (MLTI) and no cytotoxicity against autologous tumour, in agreement with previous findings. In order to investigate this depressed reactivity, we measured the effect of admixture of mitomycin‐treated TIL to PBL on PHA and MLTI responsiveness in nine individuals. Eight of these nine showed reduced reactivity to PHA (mean depression of responsiveness, 49%) and five subjects who were responsive to autologous tumour, showed markedly reduced reactivity in the presence of TIL (mean reduction, 65%). In a case of medullary carcinoma of breast it was possible to revover sufficient TIL to allow fractionation on nylon wool columns. Passage through these columns resulted in a higher level of inhibition of PBL reactivity than that seen in unpassed or column‐attached lymphocytes. These data show that TIL have suppressive activity which may account for their poor performance in other assays of effector and memory function. Copyright © 1979 Wiley‐Liss, Inc., A Wiley Company