Sousa, Ana E.Chaves, Ana F.Loureiro, AnaVictorino, Rui M. M.2015-07-142015-07-142001The Journal of Infectious Diseases 2001;184:552–90022-1899http://dx.doi.org/10.1086/322804http://jid.oxfordjournals.org/content/184/5/552.longhttp://hdl.handle.net/10451/18442© 2001 by the Infectious Diseases Society of AmericaHuman immunodeficiency virus (HIV) type 2 infection is associated with a better clinical outcome, slower rates of CD4 T cell decline, and lower viremia than is HIV-1. This study compares HIV-1 and HIV-2 in regard to the percentages of interleukin (IL)–2–, interferon (IFN)–γ–, and IL-4–producing cells at the single-cell level, as determined by flow cytometry. At a given degree of CD4 T cell depletion, the frequency of T cells able to produce IL-2 is better preserved in HIV-2 than in HIV-1 infection, particularly within the CD4 T cell subset. As described for HIV-1 immunodeficiency, HIV-2–positive patients exhibit a marked expansion of terminally differentiated effector CD8 T cells (CD28−CD27−IFN-γ+). However, the proportion of CD8 T cells able to simultaneously produce IL-2 and IFN-γ is higher in HIV-2 disease. Considering the central role of IL-2 as a lymphocyte proliferative and survival factor, these findings provide a possible immunologic basis for the distinct course of HIV-2 immunodeficiencyengjournal article