Interleukin 2 induced cytotoxicity on renal cell carcinoma. 2. Synergistic effects of interleukin 2 and interferon gamma.

In the previous paper, it was shown that interleukin 2 (IL-2) enhanced NK cell activity against renal carcinoma cell lines and fresh solid tumor cells of renal cell carcinoma (RCC) which are not susceptible to NK cells, and that IL-2 in duced a higher cytotoxicity than interferon ƒÁ (IFN-ƒÁ). The present study was carried out to examine the mechanism of the en hanced cytotoxicity of IL-2 and IFN-ƒÁ in vitro, and to investigate the effects of NK cell activity when peripheral blood lymphocytes (PBL) are simultaneously treated with these lymphokines. To test the proliferative response of PBL, 3H-TdR incorporation was deter mined. Effector lymphocytes, that proliferated in the presence of IL-2 but not in IFN-ƒÁ, required DNA synthesis for the induction. These lymphocytes also significantly increased phenotype in Leu 11+ cells (p<0.001). IFN-ƒÁ at a concentration of 80IU/ml, when added to PBL incubated with IL-2 (100 IU/ml), increases the percentage of IL-2 receptors (IL-2R) and induced a greater enhancement in NK cells activity than that incubated with IL-2 a'one. This study concluded that the combination IL-2 and IFN-ƒÁ treatment, when given to patients with RCC, might produce synergistic effects of cytotoxicity through the induction of IL-2R.