ObjectiveTo assess the characteristics of CD4 and CD8 T cells specific for HIV-1 and cytomegalovirus (CMV) antigens in untreated and treated HIV-1-infected patients.MethodsAntigen-specific T cell frequencies were determined by flow cytometric detection of antigen-induced intracellular cytokines.ResultsIn untreated patients, HIV-1-specific CD4 T cell counts in peripheral blood were less than one tenth of CMV-specific CD4 T cell counts, while the number of specific CD8 T cells was approximately the same for both HIV-1 and CMV. In patients treated with highly active antiretroviral therapy (HAART) for less than 1.5 years, HIV-1-specific CD4and CD8T cell counts were significantly lower than those in untreated patients. Perforin expression in HIV-1-specific CD8 T cells was significantly lower than that in CMV-specific CD8 T cells.ConclusionThese data indicate that HIV-1-specific T cells in HIV-1-infected patients have quantitative and qualitative abnormalities.