A triple antibody assay for the quantitation of plasma IgG subclass antibodies to acetylcholine receptors in patients with myasthenia gravis.
Monoclonal anti-human IgG subclass antibodies have been used in an immunoprecipitation assay for the determination of anti-acetylcholine receptor IgG subclasses in plasma from patients with myasthenia gravis. Solubilized acetylcholine receptors labelled with 125I-alpha-bungarotoxin were incubated with patient plasma. Monoclonal mouse antibodies to human IgG subclasses 1-4 were added to the incubation and finally precipitated with anti-mouse IgG antibody. A maximal IgG subclass precipitation of 62-76% was determined with 125I-labelled myeloma IgG subclasses 1-4 added to normal human plasma. The anti-IgG subclass antibodies were added in excess which ensured that the precipitation of IgG2, IgG3 or IgG4 were unchanged, and that of IgG1 was only reduced by 17%, when the plasma IgG concentration was increased by a factor of two. The anti-IgG subclass antibodies were highly specific for their complementary subclasses. Determination of the IgG subclass of the anti-acetylcholine receptor antibodies from 8 patients with myasthenia gravis showed that IgG1 and IgG3 antibodies are predominant. This may support the hypothesis that complement mediated lysis of the neuromuscular end-plate plays a pathogenetic role in myasthenia gravis.
D000911:Antibodies, Monoclonal; D000918:Antibody Specificity; D001323:Autoantibodies / Q000032:analysis / Q000145:classification*; D011232:Chemical Precipitation; D004306:Dose-Response Relationship, Immunologic; D006801:Humans; D007074:Immunoglobulin G / Q000145:classification*; D007158:Immunologic Techniques; D009157:Myasthenia Gravis / Q000276:immunology*; D011950:Receptors, Cholinergic / Q000276:immunology*
D000911:Antibodies, Monoclonal; D001323:Autoantibodies; D007074:Immunoglobulin G; D011950:Receptors, Cholinergic