Purification and Characterization of Multiple Components of Human Lymphoblastoid Interferon-a*

Twenty-two components of human interferon-a (IFN-a) derived from Sendai virus-induced Namalwa cells were purified by sequential immunoadsorbent affinity chromatography using four monoclonal antibody affinity columns followed by ultrafiltration and reversed-phase high-performance liquid chromatography. The specific activity ranged from 0.2 to 2.6 x lo8 IU/mg protein on Madin-Darby bovine kidney cells, 0.3 to 4.6 X lo* IU/mg protein on human WISH cells, and lo4 to 7 x lo5 units/mg protein on mouse L929 cells. The apparent molecular weights of the components ranged from 17,500 to 23,300 using nonreducing sodium dodecyl polyacrylamide-gel electrophoresis and 17,500 to 27,600 using reducing sodium dodecyl polyacylamide-gel electrophoresis. The amino-terminal amino acid sequences were similar among the components as well as to those reported for the cloned human IFN-a genes (Pestka, S. (1986) Methods Enzymol. 119, 3-14). However, four components, f, i, 1, and m, have amino-terminal amino acid sequences which appear to be unique when compared to those predicted from the cDNA clones. One component, prea, has a potential N-linked glycosylation site on the Asn of residues 2 through 4, Asn-Leu-Ser.