Tumour necrosis factors (alpha, beta) induced by HIV-1 in peripheral blood mononuclear cells potentiate virus replication.

Cytokines such as tumour necrosis factor (TNF) can induce HIV-1 production in T-cell tumour lines. However, it is not known if the same occurs in freshly isolated mononuclear cells, nor is it known if the virus can itself regulate cellular cytokine production. In this paper we report that HIV-1 induces peripheral blood mononuclear cells (PBMC) and CD4+ T lymphocytes to secrete TNF alpha, TNF beta and interferon-gamma (IFN gamma), three cytokines having multifunctional activities and complex physiological roles. We also show that separate addition of exogenous recombinant (r) TNF alpha or rTNF beta or rIFN gamma increases HIV-1-induced syncytium formation in both PBMC and CD4+ cells by up to 10,000-fold, with TNF alpha being most potent in this regard. Finally, we show that syncytium formation induced by diverse HIV-1 isolates and LAV-2 is inhibited without the addition of exogenous r-cytokines by the respective anti-cytokine antibodies. Our study therefore demonstrates that efficient HIV replication in primary mononuclear cells is associated with the ability of the virus to induce TNF and IFN gamma secretion.