Characterization of retinoblastoma immune complexes.

Immune complexes from retinoblastoma sera were characterized with molecular sieve chromatography, affinity chromatography, and polyacrylamide gel electrophoresis (PAGE). Retinoblastoma patients' sera had two well-defined peaks of immune complex activity after molecular sieve chromatography. These protein fractions had a molecular weight of approximately 1.6 x 10(5) and 2.0 x 10(6) daltons. Affinity chromatography with Sepharose 4B-protein A and analytical PAGE demonstrated that IgG was the predominant immunoglobulin in these immune compelxes. Immune complexes also had affinity for Sepharose-concanavalin A, indicating the glycoprotein nature of the antigen component.