Objectives:

Reduced dendritic cell (DC) frequencies and functions in individuals with longstanding HIV-1 infection are predictive of opportunistic infections and AIDS. To investigate possible early alterations in DC levels after HIV infection, we prospectively examined plasmacytoid dendritic cell (pDC) and myeloid dendritic cell (mDC) frequencies and plasma IFN-α levels in patients undergoing primary HIV-1 infection (PHI).

Methods:

Peripheral blood DC frequencies and absolute counts were determined by flow cytometry. Plasma IFN-α levels were measured by enzyme-linked immunosorbent assay (ELISA).

Results:

In comparison to uninfected subjects, pDC, but not mDC, levels were reduced (P< 0.001) in subjects with PHI, especially in those with high viral loads or low CD4 T-cell counts. During 24–48 weeks of observation, untreated subjects experienced slight declines in pDC and CD4 T-cell levels. In contrast, subjects initiating early antiretroviral therapy (ART) exhibited increases (P< 0.001) in pDC and CD4 T-cell counts. No effect of treatment on mDC counts was observed. Circulating plasma IFN-α was undetectable by ELISA regardless of the duration of HIV-1 infection.

Conclusion:

PHI is characterized by a reduction in pDC and CD4 T-cell counts that correlates with the magnitude of virus replication and is not evidenced by the mDC count or plasma IFN-α level. Early ART appears to have similar restorative effects on pDC and CD4 T-cell counts.