INFLUENCE OF SYSTEMIC CHEMOTHERAPY ON ANTI-P-GLYCOPROTEIN ANTIBODY-DEPENDENT CELL-MEDIATED CYTOTOXICITY IN PATIENTS WITH SMALL-CELL LUNG-CANCER

Anti-P-glycoprotein antibody (MRK-16)-dependent cell-mediated cytotoxi city (ADCC) by blood mononuclear cells (MNC) was examined in patients with small cell lung cancer (SCLC) before and after systemic chemother apy. The effect of in vitro treatment of MNC with interleukin (IL)-2 a nd macrophage-colony-stimulating factor (M-CSF) was also examined. The ADCC reaction was assessed by a 6 h Cr-51-release assay using a multi drug-resistant (MDR) SCLC cell line (H69/VP cells). The MRK-16 monoclo nal antibody was able to augment spontaneous cytotoxicity by MNC, even in SCLC patients. Pretreatment of MNC with IL-2 significantly augment ed their ADCC ability in SCLC patients, while M-CSF had no effect on A DCC activity. After the first cycle of systemic chemotherapy, the ADCC activity tended to decline, but ADCC of MNC pretreated with IL-2 was not affected. The results suggest that anti-P-glycoprotein antibody, i n combination with a cytokine such as IL-2, may be therapeutically use ful against human SCLC resistant to chemotherapeutic drugs.