Low doses of anticancer drugs increase susceptibility of tumor cells to lysis by autologous killer cells.

Pretreatment of squamous cell carcinoma (SCC) cells from four patients with low doses of cisplatin, carboplatin or 5-fluorouracil increased the susceptibility to lysis by autologous killer cells in vitro. Exposure of two SCC cell lines to low doses of these drugs increased the cell surface expression of both HLA class I and intercellular adhesion molecule-1 (ICAM-1). HLA class II, neural cell adhesion molecule and B7 were not expressed on the cell surface before or after such treatment. The results suggest that these drugs increase the susceptibility of tumor cells to autologous cell-mediated cytotoxicity, at least in part, by enhancing the expression of HLA class I and ICAM-1.