[Antitumor effector cells in recombinant IL-2 activated tumor infiltrating lymphocytes from human solid cancers]

Tumor infiltrating lymphocytes (TIL) isolated from 46 human solid cancers, including 24 renal cell carcinoma (RCC), 15 cancers of digestive organs and 7 other malignancies, were cultured with 1000 units/ml of recombinant interleukin-2 (rIL-2). Induction of activated TIL was achieved in 41 cases (89.1%). Their antitumor characteristics and cell surface antigen expressions were examined using 4 hr 51Cr release assay and flow cytometric analysis in long-term culture. Cytotoxic activity of rIL-2 activated TIL derived from RCC was significantly higher than that from other tumors, but the TIL could lyse various types of cells and specificity for autologous tumor cells could not be demonstrated in any of the cultures. Though CD3+ lymphocytes were predominant in all fresh TIL preparations, antitumor activity of rIL-2 activated TIL correlated with the increase of a cell population expressing the Leu19 antigen without the CD3 antigen. Depletion of selected cell types from TIL cultures using direct complement dependent cytolysis followed by cytotoxicity tests identified the Leu19+ CD3- CD16- cells as the major effector population. CD3-, CD16+ NK cells held minor antitumor cytotoxicity and there was no detectable cytotoxic activity in the CD3+ T lymphocytes.