Biochemical studies of immune complexes. I. Isolation of circulating immune complexes using a bifunctional exclusion chromatography matrix

Biochemical studies of immune complexes. I. Isolation of circulating immune complexes using a bifunctional exclusion chromatography matrix

A simple and rapid method of isolating immune complexes from serum is described. The method utilizes the binding properties of a bifunctional chromatography matrix consisting of diethylaminoethyl and Cibacron blue F3GA functional groups linked to agarose beads. This column matrix binds all normal serum proteins except IgG and transferrin, excluding these proteins, and permitting them to be collected in the wash-through, void volume. Immune complexes prepared in vitro with human serum albumin were rapidly isolated from starting serum by this method. This method may have general application for the purification of immune complexes from serum in pathological conditions and should foster subsequent biochemical and immunological studies, including identification and characterization of immune complex antigens.

Biochemical studies of immune complexes. II. Purification of immune complexes from sera of patients with malignant melanoma

Circulating immune complexes (CICs) from serum samples of patients with malignant melanoma were isolated in high yield utilizing a bifunctional chromatography matrix that binds all normal serum proteins except IgG-containing immune complexes (ICs), IgG, and transferrin. Protein fractions were subsequently analyzed by polyacrylamide gel electrophoresis (PAGE) and characterized by molecular weight. By this method, one common and several unique component nonimmunoglobulin proteins of the ICs were identified. These proteins possess similar molecular weights to several previously described human melanoma antigens. This technique should permit biochemical and immunological characterization of the component antigens of CICs in melanoma and other malignancies.