Soluble tumor necrosis factor receptor: inhibition of human immunodeficiency virus activation

The inflammatory cytokine tumor necrosis factor alpha (TNF-alpha) has been shown to stimulate human immunodeficiency virus type 1 (HIV-1) replication in both chronically and acutely infected T lymphocytes and monocytes. Transcriptional activation of the HIV long terminal repeat and subsequent increase in virus production are linked to TNF activation of the cellular transcription factor NF-kappa B. Here we report the use of two forms of soluble recombinant type 1 (p80) TNF receptor to inhibit TNF-induced HIV activation in vitro. One receptor form is a monomer containing the entire 236 residues of the extracellular (ligand-binding) portion of p80. A second receptor form is a chimeric homodimer containing these residues fused to a truncated human IgG1 immunoglobulin heavy chain and, thus, resembles a bivalent antibody without light chains. These recombinant receptor proteins were tested for their ability to inhibit TNF-alpha-induced expression of HIV-1 in chronically infected human cell lines. We also examined the ability of the soluble receptors to limit the activation of the HIV-long terminal repeat transcription. The soluble TNF receptor dimer was most effective at blocking TNF-alpha-induced HIV-1 expression in both monocytoid and lymphoid cells. The molar ratio of TNF-receptor dimer to TNF-alpha found to be most effective was, at least, 5:1. We conclude that at specific TNF/soluble TNF-receptor dimer ratios, TNF-alpha-induced HIV-1 transcription and expression can be limited in vitro.