Greater Expansion of IFN-− CD4+ NKT Cells in HIV-1 Compared with HIV-2-Infected Subjects with Preserved CD4+ T Cell Counts

Abstract

Context: Human Natural Killer T cells are T lymphocytes that express an invariant  T cells receptors and NK cells receptors. They regulate innate and adaptive immune response but are susceptible to HIV-1 infection. Objective: We compare the frequency and the activity of NKT cells in HIV-1 and HIV-2 infected individuals with CD4+ counts greater than 500/mm3 using flow cytometry after overnight stimulation with phytohemagglutinin (PHA). Results: The frequency of NKT cells was similar between both groups and also to sero-negative control subjects. There were also no significant differences in the proportions of total NKT cells and the CD4+ NKT subset that secreted interferon gamma (IFN-) after polyclonal stimulation. However, there was a significantly higher frequency of IFN-- CD4+ NKT cells in HIV-1-infected compared with HIV-2 infected subjects (p = 0.043). Conclusion: These data suggest there is no relationship between the functional activity of NKT cell subsets and the total NKT cell population in HIV infection. The expansion of IFN-- CD4+ NKT cells in HIV-1 infection may serve as target for viral infection and may eventually result in their depletion during chronic infection.