Higher Type 1 Interferon Levels in Plasma of Asymptomatic HIV-2 than in HIV-1 Individuals

A number of cytokines are secreted during HIV infection that enhances both innate and adaptive immune responses. Interferon-α/β/γ, IL-12, IL-15 and IL-18 have been found to contribute to the development, maturation, differentiation and function of NK and other immune cells. The levels of IFN-α/β/γ, IL-12, IL-15 and IL-18 were compared in the plasma of 90 HIV-1 infected and 90 HIV-2 infected subjects by ELISA or Cytometric Beads Array assays. The HIV-infected subjects were stratified according to CD4+ T cell counts into three groups: >500, 200 - 500 and α was found to be significantly increased in HIV-2 infected compared to HIV-1 infected subjects at high CD4+ T cell counts (p = 0.001). The levels of IFN-β were seen to differ between the two infections in patients from the category of medium CD4+ T cell counts: this was significantly increased in HIV-2 infected patients (p γ were similar at all the CD4+ T cell categories except for an increase in HIV-2 infected patients at low CD4+ T cell counts (p = 0.02). The levels of these cytokines were similar in all HIV-1 subjects. Also, the level of IL-12p70 was similar between the two infections but significantly higher in HIV-2 at low compared to medium CD4+ T cells categories (p = 0.047). Similar to IFN-γ and IL-12p70, the levels of both IL-18 and IL-15 were found to be significantly higher in HIV-2 infected patients compared to HIV-1 at low CD4+ T cell counts (p α in HIV-2 infected asymptomatic subjects is consistent with the high innate NK responses previously noted at this stage of infection.