Natural-killer group 2, member D (NKG2D) binds to a variety of
ligands, including the major histocompatibility complex (MHC) class I chain-related
proteins (MIC) and UL16-binding
proteins (ULBP). It is regarded as a co-activating receptor on NK cells, having an important role in the cell-mediated immune response to tumours. We studied the influence of
interleukin (IL)-10 on the regulation of MIC and ULBP expression on
melanoma cells, and its effect on the cytotoxic function of NK cells in vitro. Here, we show that, in the presence of
IL-10, FMS mel and BL mel cell lines decreased
MICA and ULBP2 surface expression, whereas MHC class I did not change substantially on the cell surface.
MICA mRNA levels decreased in IL-10-treated FMS and IL-10-transduced BL cell lines. Interestingly, we observed that MICB surface expression and its
mRNA levels increased upon
IL-10 treatment in a
melanoma cell line. These changes in NKG2D
ligands surface expression patterns owing to
IL-10 treatment resulted in an effect on lysis susceptibility mediated by lymphocyte-activated killer cells, as tumour cell lines that displayed a higher decrease of
MICA on their surface had lower levels of lysis. In addition, expression of CD107a was downregulated on the surface of NK cells following stimulation with IL-10-treated FMS cells. Our results suggest a novel function for
IL-10 in the modulation of NKG2D
ligand expression and in the control of cytotoxicity mediated by NKG2D/NKG2D
ligand axis.