IL-21 expands HIV-1-Specific CD8+ T memory stem cells to suppress HIV-1 replication in vitro

Abstract

Due to the existence of viral reservoirs, the rebound of human immunodeficiency virus type 1 (HIV-1) viremia can occur within weeks after discontinuing combined antiretroviral therapy. Immunotherapy could potentially be applied to eradicate reactivated HIV-1 in latently infected CD4+ T lymphocytes. Although the existence of HIV-1-specific CD8+ T memory stem cells (TSCMs) is well established, there are currently no reports regarding methods using CD8+SCMs) to treat HIV-1 infection. In this study, we quantified peripheral blood antigen-specific CD8+SCMs) and then expanded HIV-1-specific SCMs) that targeted optimal antigen epitopes (SL9, IL9, and TL9) in the presence of interleukin-(IL-) 21 or IL-15. The suppressive capacity of the expanded CD8+SCMs) on HIV-1 production was measured by assessing cell-Associated viral RNA and performing viral outgrowth assays. We found that the number of unmutated TL9-specific CD8+SCMs) positively correlated with the abundance of CD4+ T cells and that the expression of IFN-γ was higher in TL9-specific CD8+SCMs) than that in non-TL9-specific CD8+ TSCMs. Moreover, the antiviral capacities of IL-21-stimulated CD8+SCMs) exceeded those of conventional CD8+ memory T cells and IL-15-stimulated CD8+SCMs). Thus, we demonstrated that IL-21 could efficiently expand HIV-1-specific CD8+ TSCMs to suppress HIV-1 replication. Our study provides new insight into the function of IL-21 in the in vitro suppression of HIV-1 replication.