Concanavalin A reaction with human normal immunoglobulin G and myeloma immunoglobulin G.

Concanavalin A precipitated less than 5 percent of immunoglobulin G from human serum. It reacted with all of 42 myeloma serums of the immunoglobulin G type tested, but no more than approximately 50 percent of the total myeloma protein was ever precipitated. The fact that not all of the protein was precipitated and that the amounts precipitated varied from serum to serum may be interpreted as demonstrating heterogeneity of the carbohydrate in these myeloma proteins. Other glycoproteins precipitated by concanavalin A were identified, and subsequently separated from concanavalin A by chromatography.