Elevated interferon-γ–induced protein 10 and its receptor CXCR3 impair NK cell function during HIV infection

As the first line of defense in the human immune system, NK cells play essential roles in prevention of tumorigenesis and viral infection. It is known that NK cells have impaired function in HIV infection; however, it remains unclear why this occurs. IP-10 is a chemokine and inflammatory factor that is associated with such diseases as tuberculosis, hepatitis B virus, and pancreatic cancer. The aim of this study was to evaluate IP-10 levels and CXCR3 expression in NK cells that were affected by HIV and to elucidate whether NK cell function could be affected by IP-10. Our results demonstrate that IP-10 levels and expression of CXCR3 in NK cells was significantly higher in HIV-infected participants compared with noninfected participants. Moreover, the ability of NK cells to secrete IFN-γ and, specifically, to lyse K562, was suppressed with exposure to high levels of IP-10. This study also showed that CXCR3+ NK cell function decreased dramatically when treated with IP-10, which indicates that CXCR3+ NK cells were the main targets of IP-10. Furthermore, IP-10 or CXCR3 blocking could restore NK cell function. These data suggest that elevated IP-10 levels may impair NK cell function during HIV infection and that IP-10/CXCR3 blocking may be a novel therapeutic strategy in the control and functional cure of HIV.