Induction of cytokines by HIV-1 and its gp120 protein in human peripheral blood monocyte/macrophages and modulation of cytokine response during differentiation.
Laboratory of Virology, Istituto Superiore di Sanità, Rome, Italy.
We previously reported that in vitro culture of human peripheral blood monocytes resulted in a time-dependent differentiation into macrophages and in an enhanced capacity for producing certain cytokines [i.e., tumor necrosis factor alpha, interleukin-6 (IL-6), and interferon-beta (IFN-beta)] in response to bacterial lipopolysaccharide (LPS). HIV-1 infection or gp120 treatment of monocyte/macrophages resulted in the induction of low levels of IFN-beta, which were very effective in restricting viral replication in 7-day cultured macrophages but not in freshly isolated cells. This enhanced response of macrophages was due to a higher sensitivity of these cells to the antiviral effect of IFN-beta. Consistent with this finding, 7-day cultured macrophages exhibited higher levels of type I IFN receptors than 1-day cultured monocytes. Treatment of monocyte/macrophages with gp120 also caused a marked increase in IL-10 secretion, regardless of the differentiation state. No IL-12 secretion was detected in monocyte/macrophage cultures treated with gp120 alone. However, consistent IL-12 secretion was found in 7-day cultured macrophages primed with IFN-beta and subsequently stimulated with gp120. Macrophages responded more efficiently than monocytes to the priming effect of IFN-beta for IL-12 production. This was consistent with a stronger antiviral response against vesicular stomatitis virus by these cells as well as with a higher expression of IFN-beta receptors. The finding that the acquisition of the macrophage phenotype is associated with an increased capacity to respond to environmental signals (such as type I and type II IFNs) underlines the importance of the differentiation process for the selection of a certain repertoire of responses that may allow these cells to have important functions in vivo.
PMID: 9225992 [PubMed - indexed for MEDLINE]