Cytokine regulation of the human immunodeficiency virus (HIV)

The remarkable ability of HIV to insinuate itself into the working of the immune system is the key of its success as an infectious agent. Given that the cytokine network regulates the immune responses, it is not surprising that cytokines can modulate HIV infection. GM-CSF, IL6 and TNF-alpha enhance HIV, but TGF-beta and HIF inhibits the virus. However, the anti-HIV activity of TGF-beta is restricted to myeloid cells, while HIF inhibits HIV in myeloid cells and in T-lymphocytes. HIF is produced by CEM cells after induction by an extract from pine cones. It is not an interferon and is likely a novel cytokine. It is pepsin-sensitive but trypsin-resistant and has an apparent molecular weight of 7-12 KDa. Apart from having anti-HIV activity, crude preparations of HIF also inhibit HTLV-1 virus but not HSV virus replication.