Abstract
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 γ (IFN-γ).
The present study was carried out to examine the mechanism of the en-hanced cytotoxicity of IL-2 and IFN-γ 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-γ, required DNA synthesis for the induction. These lymphocytes also significantly increased phenotype in Leu 11+ cells (p<0.001).
IFN-γ 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 alone.
This study concluded that the combination IL-2 and IFN-γ treatment, when given to patients with RCC, might produce synergistic effects of cytotoxicity through the induction of IL-2R.
