TEST FOR ANTIGEN-ANTIBODY COMPLEXES IN HUMAN SERA USING IGM OF RABBIT ANTISERA TO HUMAN IMMUNOGLOBULINS

Abstract

A simple semi-quantitative test for soluble antigen-antibody complexes using characterized non-human reagents and permitting analysis of their constituents is described. The agglutination of immunoglobulin[Ig]-coated latex particles by rabbit IgM antibodies to the Ig is inhibited by complex-containing sera. No inhibition is obtained with monomer Ig. Semi-quantitative measurement of complexes may be made by electronically counting residual unagglutinated latex particles. The new method of linking proteins to latex by DNP [dinitrophenol] coupling permits the technique to be applied to all constituents of complexes; Ig, complement and antigens. A new method of decomplementing sera by EDTA-Sigma cell-IgG absorption allows analysis of sera without the false positives and false negatives other methods give. The test gave positive results for IgG complexes in most 24 patients with SLE [systemic Lupus erythematosus] nephritis. IgA complexes were identified in a patient with Henoch-Schonlein purpura nephritis.