Reduced blood CD123(+) (lymphoid) and CD11c(+) (myeloid) dendritic cell numbers in primary HIV-1 infection

Successful immunologic control of HIV infection is achieved only in rare in dividuals. Dendritic cells (DCs) are required for specific antigen presenta tion to naive T lymphocytes and for antiviral, type I interferon secretion. Two major blood DC populations are found: CD11c(+) (myeloid) DCs, which se crete IL-12, and CD123(+) (IL-3-receptor(+)) DCs (lymphoid), which secrete type I interferons in response to viral stimuli. The authors have previousl y found a decreased proportion of blood CD11c+ DCs in chronic HIV+ patients . In this study, 26 to 57 days after infection and before treatment, CD123 and CD11c+ DC numbers were dramatically reduced in 13 HIV+ patients compar ed with 13 controls (P = .0002 and P = .001, respectively). After 6 to 12 m onths of highly active antiretroviral therapy, DC subpopulation average num bers remained low, but CD123(+) DC numbers increased again in 5 of 13 patie nts. A strong correlation was found between this increase and CD4 T-cell co unt increase (P = .0009) and plasma viral load decrease (P = .009). Reduced DC numbers may participate in the functional impairment of HIV-specific CD 4(+) T cells and be responsible for the low type I interferon responsivenes s already known in HIV infection. The restoration of DC numbers may be pred ictive of immune restoration and may be a goal for immunotherapy to enhance viral control in a larger proportion of patients. (C) 2001 by The American Society of Hematology.