Immunologic and virologic evaluation after influenza vaccination of HIV-1-infected patients

The present study was designed to determine the effect of immune activation, achieved by influenza vaccination, on plasma HIV RNA levels and immunological parameters including CD4 cell levels, antigen-stimulated T-cell function and apoptotic death of peripheral blood mononuclear cells.

Thirty-four HIV-infected individuals and nine uninfected controls were immunized with influenza vaccine and blood was collected at weeks 0, 2, 4 and 16. Plasma was isolated and used for HIV RNA and influenza-specific antibody qualifications. CD4 cell counts, activation and maturation markers of T-lymphocyte subsets were determined by flow cytometry. In vitro T-helper responses, spontaneous- and activation-induced cell death assays were also performed.

Influenza-specific humoral and cellular immune responses correlated with CD4 count. Only in patients with CD4 counts > 300 x 10(6)/l there was a modest increase in T-cell responses to influenza virus, which was less than control subjects, observed after vaccination. Immunization had no significant effect on CD4 counts or plasma viral levels in the HIV-positive patients. Baseline apoptosis inversely correlated with CD4 counts and directly correlated with viral load. Activation-induced apoptosis did not change appreciably after vaccination and spontaneous apoptosis increased only in the < 300 CD4 group.

These results indicate that immune stimulation resulting from influenza vaccination did not significantly change the levels of plasma virus, CD4 cell counts, or activation-induced apoptosis in HIV-infected individuals, although an increase in the T-cell response to influenza and spontaneous apoptosis was observed in the > 300 and < 300 CD4 groups, respectively.