Human acid- and thermolabile alpha-interferon-like substance: selective reactivity with a monoclonal antibody.

An acid- and thermolabile alpha-interferon-like substance, designated AL-IFN-alpha, has been found in non-processed normal human leukocyte IFN preparations as well as sera from patients with autoimmune or other chronic diseases. Little is known about origin, production and biological activity of these IFN activities. Monoclonal antibodies were obtained which proved highly selective in neutralizing AL-IFN-alpha in both anti-proliferative and antiviral tests. While the monoclonal antibodies were strict specific, polyclonal antibodies against various interferons showed less specificity in these tests. The results suggest that AL-IFN-alpha represents an antigenically distinct IFN-alpha subtype or, alternatively, a new lymphokine with antiproliferative and antiviral activity.