Circulating CD8 T Cells Show Increased Interferon-γ mRNA Expression in HIV Infection

IFN-γ mRNA levels were measured in unstimulated PBMC and purified cell subpopulations, utilizing branched DNA assays, to characterize the cell type(s) that contribute to thein vivoincrease in IFN-γ gene expression seen in HIV infection. PBMC and CD8 T cells from HIV-seropositive subjects (HIV+) showed 2.5-fold increases in mean IFN-γ mRNA levels compared to HIV-uninfected subjects (HIV−). Within individuals, CD8 T cells showed the highest IFN-γ expression regardless of HIV status, which suggests that HIV infection enhances the IFN-γ gene expression in CD8 T cells rather than inducing a shift to and/or increasing expression of IFN-γ mRNA in other cell types. HIV+subjects with increased PBMC IFN-γ mRNA had elevated plasma levels of HIV RNA, neopterin, and β2-microglobulin. No differences in IFN-γ mRNA levels were seen among HIV+stratified by CD4 T cell number. Increased IFN-γ may result from or be a contributing factor to increased viral load.