Notably, none of the 14 NKG2C+ or 16 NKG2C−/− HCMV seronegative donors harbored such expansions (data not shown), suggesting that, like NKG2C+ donors, the expansions observed in NKG2C−/− individuals were related to HCMV infection. This evidence concerns the gene KLRC2 and cytomegalovirus infection.