Early proliferation of CCR5+ CD38+++ antigen-specific CD4+ Th1 effector cells during primary HIV-1 infection

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Abstract
We investigated whether HIV-1 antigen-specific CD4+ T cells expressed the viral coreceptor CCR5 during primary HIV-1 infection (PHI). In the peripheral blood of subjects with very early PHI (< 22 days after onset of symptoms), there was a 10- to 20-fold increase in the proportion of highly activated (CD38+++) and proliferating (Ki-67+) CD4+ T cells that expressed CCR5+, and were mostly T-cell intracellular antigen-1 (TIA-1)+ perforin+ granzyme B+. Inthe same patient samples, CD4+ T cells producing interferon (IFN)–γ in response to HIV group-specific antigen (Gag) peptides were readily detected (median, 0.58%) by intracellular cytokine assay—these cells were again predominantly CD38+++, Ki-67+, and TIA-++, as well as Bcl-2low. On average, 20% of the Gag-specific CD4+ T cells also expressed interleukin-2 (IL-2) and were CD127 (IL-7R)+. Taken together, these results suggest that Gag-specific T-helper 1 (Th1) effector cells express CCR5 during the primary response and may include precursors of long-term self-renewing memory cells. However, in PHI subjects with later presentation, antigen-specific CD4+ T cells could not be readily detected (median, 0.08%), coinciding with a 5-fold lower level of the CCR5+CD38+++ CD4+ T cells. These results suggest that the antiviral response to HIV-1 infection includes highly activated CCR5+CD4+ cytotoxic effector cells, which are susceptible to both apoptosis and cytopathic infection with HIV-1, and rapidly decline.