Interferon-induced 2'-5' oligoadenylate synthetase during interferon-alpha therapy in homosexual men with Kaposi's sarcoma: marked deficiency in biochemical response to interferon in patients with acquired immunodeficiency syndrome.

Titers of circulating interferon (IFN) and the activity of 2'-5' oligoadenylate (2-5A) synthetase, an enzyme specifically induced by IFN, were measured in 28 homosexual men with acquired immunodeficiency syndrome (AIDS) who received one- to six-month courses of antineoplastic therapy with IFN-alpha and in homosexual and heterosexual controls. Fifteen of the patients and two of seven healthy homosexual men had high endogenous levels of 2-5A synthetase. IFN therapy induced further increases in this enzyme in only 10 of the 28 patients with AIDS. Furthermore, peripheral blood cells from all but one of the patients with AIDS and homosexual controls tested were markedly deficient in their ability to respond to IFN in vitro, as measured by increased levels of 2-5A synthetase. We did not find a statistical correlation between cytomegalovirus viremia and pretherapy endogenous circulating IFN, nor any apparent correlation between disseminated infection with cytomegalovirus and either basal levels of 2-5A synthetase or changes in enzyme level during therapy. Pretherapy circulating IFN was significantly correlated with progressive Kaposi's sarcoma during therapy, but rises in levels of 2-5A synthetase were not sufficient to predict a good clinical response.