Differentiation of monocytes into CD1a- dendritic cells correlates with disease progression in HIV-infected patients.

Monocyte differentiation into dendritic cells (DCs) depends on microenvironmental conditions. In this study, the capacity of human monocytes to differentiate into mature DCs and their ability to induce an antiviral immune response was investigated in HIV-infected patients. In healthy subjects, monocytes differentiate into CD1a(+) DCs in the presence of granulocyte macrophage colonystimulating factor and interleukin (IL)-4 and matured in the presence of lipopolysaccharide. Here, we found that in 30% and 45% of HIVinfected white and African subjects, respectively, monocytes gave rise to a homogeneous CD1a(-) DC population. In the patients who gave rise only to the CD1a(-) DCs, this population spontaneously produced IL-10 but not IL-12, and induced a T helper 2-like immune response when cultured with human T cells isolated from cord blood mononuclear cells. In patients with monocytes differentiated into CD1a(-) DCs, a high percentage of HIV-specific CD4(+) T cells producing IL-4 were seen in the peripheral blood. Furthermore, differentiation of monocytes into DCs with CD1a(-) phenotype correlated with low CD4(+) T-cell counts and high viral loads in HIV-infected subjects. These results suggest that the differentiation of monocytes into CD1a(-) DCs may be a phenotypic marker associated with progression of the disease.