Natural Killer Cell Cytotoxicity and Immunosuppressive Cytokines (IL-10, TGF-β1) in Patients with Gastric Cancer

Cytotoxic activity of NK cells was estimated as related to IL-10 and TGF-β1 serum levels and Helicobacter pylori infection in gastric cancer patients. Moreover, we sought to determine whether human gastric adenocarcinoma cells in vitro release IL-10, TGF-β1 or factor(s) affecting NK cytotoxicity. The studies were conducted on 42 patients with gastric cancer (14 with I-II stage—group 1; 28 with III-IV stage—group 2) and on 20 healthy volunteers. The cytotoxicity was tested on NK cells isolated from peripheral blood. IL-10 and TGF-β1 levels were determined by ELISA. H. pylori was detected in cultures of gastric mucosa biopsies and in direct preparations. In 71.4% patients of group 1 NK cytotoxicity and IL-10 serum levels remained within a normal range while in 68% patients of group 2 a marked decrease was noted in cytotoxic function of NK cells, accompanied by increased levels of IL-10 in serum. In turn, in most patients of either group, independently of NK cytotoxicity and stage grouping in the patients, elevated serum levels of TGF-β1 were detected. Presence of H. pylori infection manifested no relationship with NK cytotoxicity, IL-10, or the TGF-β1 serum levels. In cultures of tumour cells presence of IL-10 and TGF-β1 was demonstrated. Nevertheless, supernatants of the cultures did not change cytotoxic activity of NK cells. Development of gastric carcinoma is accompanied by markedly decreased cytotoxic function of NK cells and by elevated IL-10 and TGF-β1 serum levels. Gastric carcinoma cells may release IL-10, the suppressive activity of which may in a secondary manner decrease NK cytotoxicity.