Desensitization to type I interferon in HIV-1 infection correlates with markers of immune activation and disease progression.

Type I interferon (IFNalpha/beta) plays a complex role in HIV-1 infection and has been proposed alternately to have roles in either disease protection or progression. Although IFNalpha/beta plays crucial roles in regulating monocytes and dendritic cells, responsiveness of these cells to IFNalpha/beta in HIV-1 infection is poorly understood. We report significant defects in IFNalpha/beta receptor (IFNalpha/betaR) expression, IFNalpha signaling, and IFNalpha-induced gene expression in monocytes from HIV-1-infected subjects. IFNalpha/betaR expression correlated directly with CD4+ T-cell count and inversely with HIV-1 RNA level and expression of CD38 by memory (CD45RO+) CD8+ T cells, a measure of pathologic immune activation in HIV-1 infection associated with disease progression. In addition, monocytes from HIV-1-infected persons showed diminished responses to IFNalpha, including decreased induction of phosphorylated STAT1 and the classical interferon-stimulated gene produces MxA and OAS. These IFNalpha responses were decreased regardless of IFNalpha/betaR expression, suggesting that regulation of intracellular signaling may contribute to unresponsiveness to IFNalpha/beta in HIV-1 disease. Defective monocyte responses to IFNalpha/beta may play an important role in the pathogenesis of HIV-1 infection, and decreased IFNalpha/betaR expression may serve as a novel marker of disease progression.