RECOMBINANT HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 (HIV-1) TAT PROTEIN INHIBITS PHAGOLYSOSOMAL FUSION IN HUMAN PERIPHERAL-BLOOD MONOCYTES

The effect of recombinant HIV-1 Tat protein on different functions of peripheral blood monocytes, such as candidacidal activity and phagolys osomal fusion, was evaluated. HIV-1 Tat protein caused a significant i mpairment of phagolysosomal fusion at 100 ng/ml (p = 0.018). The inhib itory effect of Tat on phagolysosomal fusion was blocked by the additi on of 1 mu g/ml monoclonal anti-Tat antibody. Candidacidal activity of peripheral monocytes was not altered by HIV-1 Tat protein at the conc entration of 1 mu g/ml. These results indicate that HIV-1 Tat protein can affect the monocyte microbicidal mechanisms at the phagolysosomal fusion step with little or not effect upon the lytic activity.