The hyperviscosity syndrome in rheumatoid arthritis due to intermediate complexes formed by self-association of IgG-rheumatoid factors

Three patients with rheumatoid arthritis and abundant circulating intermediate complexes were studied. Two of these patients presented with the hyperviscosity syndrome. All 3 patients had markedly elevated plasma and blood viscosity, and the intermediate complexes were thought to be responsible for the increased viscosity. Studies on the isolated intermediate complexes revealed that they were formed by self-association of IgG-rheumatoid factors.