A circulating complex between ASAT and IgG in serum in an apparently healthy woman.

An elevated level of serum aspartate aminotransferase (ASAT) activity in a subjectively healthy woman was shown to be due to circulating ASAT:IgG complexes. The complexes were demonstrated by taking advantage of the specific interaction between protein A and IgG. Thus, greater than 90% of the patient's ASAT activity in serum could be bound to protein A-Sepharose demonstrating that nearly all the patient's serum ASAT was complexed to IgG. The ASAT-binding capacity of patient serum was calculated as approximately 850 micrograms ASAT/l which corresponds to about 0.01% of patient's IgG.