CXCR6⁺ natural killer cell immunotherapy preserves CD4⁺ T helper cells in humanized mice

Human immunodeficiency virus (HIV) persists despite antiretroviral therapy because long-lived viral reservoirs are not eliminated, and ongoing or rebound infection contributes to progressive loss of CD4⁺ T helper cells. Natural killer (NK) cells can acquire adaptive, antigen-experienced functions, including recall responses to HIV envelope protein, suggesting that defined NK-cell subsets may be therapeutically useful against HIV. Because HIV-responsive adaptive NK-cell activity is enriched among CXC chemokine receptor 6-positive (CXCR6⁺) NK cells, we tested whether CXCR6⁺ NK cells provide enhanced antiviral activity and CD4⁺ T-cell protection compared with CXCR6^- NK cells. In co-cultures with HIV-infected primary CD4⁺ T cells, PBMC-derived CXCR6⁺ and CXCR6^- NK cells both reduced viral replication, but CXCR6⁺ NK cells mediated significantly greater suppression. In HIV-infected humanized mice, weekly infusion of expanded PBMC-derived NK cells lowered plasma viral burden, with CXCR6⁺ NK cells providing stronger preservation of circulating CD4⁺ T cells and significant preservation of splenic CD4⁺ T cells. HIV-Env vaccination further enriched NK cells with enhanced therapeutic activity. CXCR6⁺ NK cells derived from HIV-Env-vaccinated humanized mice produced the strongest suppression of HIV replication and restored CD4⁺ T-cell frequencies in blood and spleen to levels comparable to uninfected controls. Together, these findings identify CXCR6⁺ NK cells as an HIV-responsive adaptive NK-cell subset that combines antiviral activity with preservation of CD4⁺ T-cell immunity in vivo. These data support further development of CXCR6⁺ NK-cell therapy as a vaccine-informed cellular immunotherapy strategy for HIV.