Elevated KIR expression and diminished intensity of CD7 on NK cell subsets among treatment naïve HIV infected Ethiopians

Natural killer (NK) cells are crucial effector cells of the innate immune response to viral infections, including HIV, through cytolytic activity and the production of cytokines with anti-HIV activities. We recruited 15 treatment naïve HIV patients and 16 healthy controls (HC) to assess NK cell subsets or expression of multiple markers by flow cytometry. The frequency of circulating CD56(bright)CD16(−ve) and CD56(dim)CD16(bright) NK cell subsets was significantly lower among the HIV group than in HC. The CD56(−ve)CD16(bright) subset was higher in HIV patients, but this was only apparent when gated among total NK cells, not total lymphocytes. NK cells among HIV participants also showed a lower and higher frequency of CD8 and HLA-DR expressing cells, respectively. In addition, CD7 median fluorescent intensity and CD2(+)CD7(−) frequencies were significantly lower in HIV patients. A distinct population of KIR3DL1/S1 cells was unexpectedly higher among CD56(bright)CD16(−ve) NK cells in HIV patients. In conclusion, this study in the Ethiopian setting confirms many previous findings, but the down-regulation of CD7 and enhanced KIR3DL1/S1 within the CD56(bright) subsets have not been widely reported among HIV patients and merit further research.