Peripheral blood dendritic cells are not a major reservoir for HIV type 1 in infected individuals on virally suppressive HAART

Dendritic cells ( DCs) are potent antigen- presenting cells, and their physiological localization in tissues that interact with the external environment is important as a first barrier against pathogens such as human immunodeficiency virus type I ( HIV- 1). Several models have been proposed to explain the possible role of DCs as a reservoir for HIV- 1 in patients on virally suppressive highly active antiretroviral therapy ( HAART). However, the low yield of cell isolates has made this evaluation a difficult task. The present study analyzes whether peripheral blood DCs from HIV- 1- infected individuals on virally suppressive HAART, with plasma HIV- 1 RNA levels of less than 50 copies/ ml, carry either HIV- 1 provirus and/ or HIV- 1 virions. Peripheral blood DCs were isolated from a cohort of 10 HIV- 1- seropositive men taking suppressive HAART. In five patients, plasmacytoid and myeloid dendritic cells were isolated to attempt to identify their respective roles in HIV- 1 residual disease. Viral out- growth assays were performed in vitro, as well as gag and R/ U5 polymerase chain reaction ( PCR) amplification of viral RNA and DNA, respectively, from DC and peripheral blood mononuclear cell ( PBMC) extracts. Fluorescence activated cell- sorting ( FACS) data revealed cellular yields from 85.90 to 95.18%, of relatively pure DCs isolated from patients' PBMCs. Although HIV- 1 RNA gag and DNA RU/ 5 were detected in all PBMC samples isolated from the patients, proviral DNA and viral RNA forms were not detected in any of the DC isolates. In addition, no replication- competent virus was demonstrated in DC coculture assays, while virus was isolated from each patients' CD8(+) T- lymphocyte- depleted PBMC cocultures. Furthermore, HIV- 1 gag proviral DNA was not detected in either plasmacytoid or myeloid DC subfractions. The current study suggests that in HIV- 1- infected individuals treated with suppressive HAART, peripheral blood DCs do not carry HIV- 1 proviral DNA or viral particles attached to their surface. These populations of peripheral blood DCs are likely not a major HIV- 1 reservoir in patients on HAART with clinically undetectable plasma viral RNA.