IgG Rheumatoid Factor in Serum of Rheumatoid Arthritis Patients

Abstract

The ability of isolated IgG and F(ab)₂ fragments to agglutinate IgG-coated latex particles was used as a test of IgG-RF activity. No definite differences could be proved between controls and RF-negative RA patients, whereas the latex titres of IgG and F(ab)₂ of sero-positive RA patients were higher. The IgG latex activity was recovered in the fractions between the 19 S and 7 S after gradient centrifugation of serum or isolated IgG at pH 7.2 and within the 7S fraction after centrifugation at pH 4.1. The dissociated IgG complexes reformed after neutralization, thus indicating a self-association of the IgG molecules.