HIV long-term non-progressors maintain brisk CD8 T cell responses to other viral antigens

To examine the specificity of heightened CD8 cell responses in HIV-1-infected long-term non-progressors.

Cross-sectional study examining CD8 cell responses to hepatitis C virus (HCV) peptides in HCV-HIV LTNP (n = 6), HCV-HIV progressors (n = 11), HCV singly infected patients (n = 32), HCV singly infected patients with self-limited disease (n = 10), HIV singly infected progressors (n = 7) and HCV-negative, HIV-negative controls (n = 10).

The frequency of HCV-reactive interferon gamma-producing cells in peripheral blood was assayed by enzyme linked immunospot assay using a panel of 61 HCV-1-derived peptides.

Five of six HCV-HIV LTNP had HCV-specific CD8 responses. In contrast, responses were observed in 2 of 32 HCV singly infected patients, 2 of the 10 HCV singly infected patients with self-limited disease, and 0 of 11 HCV-HIV progressors (P < 0.001). Both frequency of HCV-specific CD8 cells and number of HCV peptides recognized were greater in HCV-HIV LTNP than in other groups.

HIV-infected LTNP maintain heightened CD8 cell responses to HCV in addition to heightened HIV specific responses. Common mechanisms may underlie preservation of CD8 immune responses in these individuals. An improved understanding of these mechanisms will help to gain insight into protective antiviral immunity as well as to the means whereby these viruses impair host defenses.