Some HIV patients who previously experienced severe immunodeficiency retain low pathogen-specific T-cell responses despite a virological response to antiretroviral therapy (ART). To identify correlates with dysfunction in accessory cell populations, HIV patients were stratified into groups maintaining high or low CD4(+) T-cell IFN-gamma responses to cytomegalovirus (CMV) over 4-8 years on ART. Myeloid dendritic cells (mDC), plasmacytoid (p) DC, M-DC8(+) cells and monocytes were enumerated and mRNA of cytokines and activation molecules were quantitated in purified subpopulations. Proportions of pDC were lower (p=0.043) and mDC were higher (p=0.043) in low responders. TRAIL receptor 2 (DR5) mRNA levels in pDC (p=0.0008) and mDC (p=0.0062) were lower in high responders compared to controls. Levels of IL-15 mRNA were higher in mDC from high responders (p=0.015) and levels of IL-10 mRNA were higher in M-DC8(+) cells from low responders (p=0.036). Hence CMV-specific CD4(+) T-cell IFN-gamma responses may be affected by numbers and function of circulating DC.