Interferons: cytokines in autoimmunity.

The presence of circulating interferons in the blood of patients with autoimmune diseases and the acquired immune deficiency syndrome (AIDS) raises the question of their possible pathogenetic or defence functions. Interferons control levels of HLA class I and II antigens on cells and can activate or inhibit immune killer cell activities. Tumour necrosis factors (TNF) and interleukin 1 induce a new autocrine species of interferon known as IFN-beta-2 whose gene has been cloned, sequenced and expressed. This IFN mediates the increase in HLA expression caused by TNF as well as the antiviral activity of this cytotoxin.