Immuno-modulating properties of interferons.

Interferons (IFNs), by inducing the antiviral state in cells, are in the first line of defence against virus infections and are therefore part of the immune system as defined in its broadest sense. In addition, IFN-alpha and beta can influence specific functions of lymphocytes and macrophages; moreover, a special class of interferons, called IFN-gamma, are produced as a result of antigen recognition by T cells and by the interaction of mitogens and lymphocytes. Interferons influence B and T cell function in vitro and in vivo, as demonstrated by their effects on antibody formation, specific cytotoxicity of sensitized T cells, allograft survival, delayed-type hypersensitivity and graft-host reaction. They stimulate Natural Killer cell activity and induce functional and morphological changes in mononuclear phagocytes. There are many examples of disturbed immune reactions as a result of viral infection, implicating interferons as contributing factors; this is a result of the lack of immunological specificity of interferon action. The extent to which interferons have a truly immunoregulatory role is a question currently receiving a great deal of attention, but is still very much unsettled.