Albumin-immunoglobulin complexes in human serum: classification and immunochemical analysis.
A complex between serum albumin and immunoglobulins was observed on immunoelectrophoresis in six patients. Two patients with multiple myeloma had monoclonal IgA-albumin complexes; one of these complexes was formed by covalent bonds and the other by non-covalent bonds. Four patients displayed non-covalent IgG-albumin complexes: of these, one had multiple myeloma, two had been treated with nitrofurantoin for prolonged periods, and one had diabetes mellitus. The IgG-albumin complex of the last patient was subjected to a detailed immunochemical analysis. The albumin-specific antibodies were isolated by affinity chromatography and analysed, using a sensitive tritium labelling technique. The antibodies were polyclonal, complexed with serum albumin through their Fab portion, and showed a high specificity for the human albumin as compared with bovine and rabbit albumins. The serum albumin of two patients displayed an abnormal behaviour in reduced SDS-polyacrylamide gel electrophoresis (PAGE). The abnormal albumins had an apparent molecular weight of 52,000 and could react with rabbit anti-human serum albumin like the normal protein. No abnormal albumin could be detected in 20 other patients' sera, including nitrofurantoin-treated patients and normal controls. These findings suggest a possible role for an altered self-component in the triggering of a specific autoimmune reaction.
D000818:Animals; D001666:Binding Sites, Antibody; D002846:Chromatography, Affinity; D003920:Diabetes Mellitus / Q000276:immunology; D004591:Electrophoresis, Polyacrylamide Gel; D000939:Epitopes; D006801:Humans; D006942:Hypergammaglobulinemia / Q000276:immunology; D007105:Immune Complex Diseases / Q000145:classification* / Q000276:immunology; D007070:Immunoglobulin A; D007140:Immunoglobulin Fab Fragments; D007074:Immunoglobulin G / Q000378:metabolism; D007136:Immunoglobulins / Q000276:immunology*; D011485:Protein Binding; D011704:Pyelonephritis / Q000276:immunology; D011817:Rabbits; D012709:Serum Albumin / Q000276:immunology* / Q000378:metabolism
D000939:Epitopes; D007070:Immunoglobulin A; D007140:Immunoglobulin Fab Fragments; D007074:Immunoglobulin G; D007136:Immunoglobulins; D012709:Serum Albumin