Abstract
Differences in innate immune responses may be associated with different capabilities of controlling HIV infection, not necessarily reflected by CD4+ T-cell counts alone. We investigated by cytofluorometry the expression of NK cell receptors and ligands in 19 treated HIV-infected patients with CD4+<220ml–1 at presentation (11 AIDS, 8 non-AIDS) and 10 healthy donors. Expression of NKp46 and NKp30 was significantly higher in non-AIDS vs. AIDS patients. Overall, the level of NKp46 expression directly correlated with the degree of NK cell cytotoxicity. As compared to healthy donors, in both groups, there was a similar increase of CD69 and HLA-DR expression in NK cells that directly correlated with the presence of activation markers (HLA-DR) on CD4+ and CD8+ T cells. As compared to AIDS, in non-AIDS patients in vitro activated CD4+ showed higher expression of MIC-A (NKG2D ligand), with significantly higher Nectin-2/DNAM-1 and MIC-A/NKG2D ratios. Thus, NK cell responses in AIDS and non-AIDS patients with similar CD4+ counts significantly differ despite similar treatment. This suggests an involvement of innate mechanisms, in preventing AIDS-defining opportunistic infections in HIV infection and further suggests, that CD4+ absolute counts alone, may be inadequate to explain differences in the clinical outcome.
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