Functional T cell subsets contribute differentially to HIV peptide-specific responses within infected individuals: correlation of these functional T cell subsets with markers of disease progression.

Using a dual color ELISPOT assay able to detect HIV-specific IFN-gamma, IL-2 and dual IFN-gamma/IL-2 secreting lymphocytes we screened for HIV peptide-specific responses directed against the entire HIV proteome in two groups of untreated HIV-infected individuals, slow progressors (SP) and progressors. We found that the three functional lymphocyte subsets contributed differentially to individual HIV peptide-specific responses within a study subject. Among the identified stimulatory peptides, a higher proportion induced dual IFN-gamma/IL-2 secretion in SP than progressors. While the magnitude of single IFN-gamma secreting lymphocytes is similar between groups, the magnitude of peptide-specific dual IFN-gamma/IL-2 secreting lymphocytes is significantly more intense in SP. Neither single nor total IFN-gamma secreting cell magnitude and breadth measurements correlated with CD4 cell count or viral load whereas both parameters of dual IFN-gamma/IL-2 secreting responses correlated positively with CD4 counts and negatively with viremia.