Activated T cells inhibit NK cell-mediated tumour rejection

Abstract

Previous studies have described the regulation of some T-cell subsets toward natural killer (NK) cells. Naturally occurring CD4(+)CD25(+) T regulatory cells can inhibit NK cell cytotoxicity, while activated interleukin-2 (IL-2) secreting T cells can stimulate NK cells. However, little is known about the impact of the integrity T-cell population on the final outcome of NK cell cytotoxicity. We thus examined the possible role of activated T cells in affecting NK cell cytotoxicity by mixed lymphocyte co-cultures in vitro and a B16 melanoma tumour model in vivo. In our study, activated T cells were found to be able to significantly inhibit NK cell cytotoxicity in vitro and blunt NK cell-mediated tumour rejection in vivo. The inhibition of NK cell function is a cell-cell contact dependent way. Results suggest that activated T cells may play an important role in limiting NK cell functions, which might be very significant for the design of biotherapy against tumour or infection in future.