Acid-labile alpha interferon. A possible preclinical marker for the acquired immunodeficiency syndrome in hemophilia.

Many homosexual men with the acquired immunodeficiency syndrome (AIDS) have an unusual acid-labile form of human leukocyte, or alpha, interferon in their serum. Male patients with classic hemophilia treated with lyophilized clotting-factor concentrates are also at high risk for the development of AIDS. To determine whether the level of alpha interferon may be a preclinical marker of early subclinical disease, we examined stored plasma and serum from three hemophilic patients with AIDS. Persistently elevated levels of the acid-labile form of alpha interferon were found in all three patients. In two patients the appearance of circulating alpha interferon preceded the onset of clinical disease by 3 to 10 months. In contrast, alpha-interferon levels were not elevated in 43 of 46 unselected patients with hemophilia; three of these patients had transient elevations. These results suggest that acid-labile alpha interferon may be a marker that can be used to identify affected asymptomatic members of high-risk groups before the onset of clinical disease.