INHIBITION OF HUMAN-IMMUNODEFICIENCY-VIRUS REPLICATION IN DIFFERENTIATING MONOCYTES BY INTERLEUKIN-10 OCCURS IN PARALLEL WITH INHIBITION OFCELLULAR RNA EXPRESSION

The mechanism of inhibition of HIVBa-L replication by interleukin 10 ( IL-10) in primary monocytes and macrophages at various stages of matur ation was investigated using semiquantitative PCR for reverse-transcri bed HIV DNA, and Northern hybridization for HIV mRNA expression in com parison with extracellular p24 antigen, Pretreatment of monocytes with IL-10 markedly inhibited expression of both unspliced and spliced HIV RNA, reaching a nadir at 7 days and recovering to normal levels by 10 days after a single application, The optimum inhibitory concentration was 25 ng/ml, Less inhibition of HIV RNA expression was observed when IL-10 was added after HN infection of monocytes and the inhibitory ef fect progressively declined to negligible levels as monocytes matured into macrophages over 10 days. IL-10 also downregulated the expression of cellular genes, including the transferrin receptor, 28S rRNA, and GAPDH, The kinetics of the inhibition of cellular mRNAs correlated wit h the inhibition of HIV RNA and also declined as monocytes matured int o macrophages. In contrast, IL-10 did not inhibit cellular mRNA expres sion in the macrophage cell line THP-1, Neutralizing polyclonal antibo dy to IL-10 reversed all its inhibitory effects, Interaction of IL-10 and TNF-alpha in combination were generally antagonistic in their effe cts on HIV transcription, IL-10 prevented stimulation of HIV RNA expre ssion by TNF-alpha after preincubation with monocytes for 48 hr, IL-10 had no effect on the levels of HIV cDNA or the process of initiation and completion of reverse transcription, The inhibitory effect of IL-1 0 on HIV replication in maturing monocytes was probably mediated mainl y by inhibition of cellular gene expression and inhibition of maturati on of monocytes into macrophages and their activation, with consequent downregulation of HIV mRNA.