Rapid assay for immune complex bound antigens from urine of cancer patients

Concentrated urine from patients with various types of cancer was fractionated by S-500 gel filtration chromatography to yield high molecular weight (mw) immune complexes (IC) and lower mw immunoglobulin (Ig) fractions. Column fractions were assayed for the presence of IgM and IgG by immunoblot probing using anti-human IgM and anti-human IgG alkaline phosphatase conjugates. These results were used to define IC fractions (those from high mw S-500 fractions which were positive for immunoglobulin) and Ig fractions (those from medium mw S-500 fractions which were positive for immunoglobulin). Antigen components of high mw S-500 IC fractions were then determined by immunoblot probe using medium mw S-500 Ig fractions as the antibody probe (i.e. autoantibody). This method for identification of immune complex antigens has the potential to probe for tumor-associated antigens, autoantigens, or foreign antigens from starting material which contains both immune complex and free immunoglobulin.