MONOCYTES MODULATE ENHANCEMENT OF HIV-1 REPLICATION BY MYCOBACTERIUM-TUBERCULOSIS

To investigate the effects of Micobacterium tuberculosis on HIV-1 repl ication, peripheral blood mononuclear cells (PBMC) of bacille Calmette -Guerin (BCG)-vaccinated donors and non-BCG-vaccinated donors were inf ected in vitro with a lymphotropic isolate of HIV-I and cultured in th e presence of purified protein derivative (PPD). Addition of PPD resul ted in enhanced HIV-I replication and lymphoproliferation in BCG-vacci nated donor PBMC, while PPD had no such effects in control PBMC. HIV-1 replication increased even more when monocytes were removed from PBMC , while lymphoproliferation was decreased. High percentages of monocyt es were associated with a decreased HIV-1 replication and proliferatio n that could not be reversed by addition of antibodies against the cyt okines IL-I, transforming growth factor-beta (TGF-beta) or indomethaci n. PPD stimulates PBMC to release IL-10, a cytokine known to down-regu late proliferation and HIV-1 replication. PPD-induced effects on proli feration as well as HIV-1 replication could be partially blocked by ad ding a monoclonal antibody against MHC class II molecules, suggesting that part of the mechanism of PPD-induced enhancement is T memory cell activation.