Are the acid-labile interferon alpha and interferon omega-1 identical?

The interferon (IFN) activity found in human leukocyte IFN alpha preparations, autoimmune and AIDS sera, and others was reported to have distinct antigenic and deviating biological properties. This led to its vague designation as acid-labile and thermolabile IFN alpha. However, using specific monoclonal antibodies, the acid-labile component of IFN alpha (not exposed to pH 2) and recombinant IFN omega 1 showed significant relatedness. Monoclonal antibody T19, generated with virus-induced leukocyte IFN alpha that had not been exposed to pH 2, neutralized both the antiviral and antiproliferative activities of IFN omega-1, and vice versa; monoclonal antibody OMG 5, specific for recombinant IFN omega-1, cross-neutralized the antiviral and antiproliferative effects of the acid-labile component of leukocyte IFN alpha. When these two IFN preparations were incubated at pH 2 for 72 hr, their biological activity significantly decreased.