Human Leukemia Antigen. II. Purification

Summary

Cytotoxicity inhibition of leukemia-specific antisera was used to measure antigenic activity in papain digests from human lymphomas. The antigen has been found on human lymphoma tissue, human leukemia cells, and cultured RAJI cells, but not on normal cells. The crude papain digests could be purified rapidly by affinity chromatography with concanavalin A bound to Sepharose 48. The leukemia antigen bound to the affinity column showed that it was a glycoprotein. The mean inhibitory dose (1050) of the crude antigen was 0.017 µg/µI, whereas the 1050 of the purified material was 0.004 µg/ml. The purified antigen labeled with ^l25I yielded essentially one peak on 12 and 15% sodium dodecyl sulfate polyacrylamide gel electrophoresis either with or without reduction with 2-mercaptoethanol. The molecular weight of the antigen from these gels was estimated to be ≈27,000. Native analytic polyacrylamide gel electrophoresis was not possible because of aggregation of the antigen even in the presence of 8 m urea. Limited preparative electrophoresis showed essentially one peak of antigenic activity. The possible clinical uses of the purified antigen were discussed.