[Serum immunoglobulin patterns in rheumatoid arthritis]

Immunoglobulins were estimated quantitatively in sera from patients with rheumatoid arthritis. According to the significantly increased immunoglobulin class(es), in RA patients as compared to normals the following immunoglobulin patterns were registered: IgG pattern, IgM pattern, IgA pattern, IgG-IgM-IgA pattern, IgG-IgM pattern and IgG-IgA pattern. The IgG-, IgA- and IgG-IgM-IgA patterns were predominantly found in sera from patients with seropositive RA. A positive correlation was found between other inflammatory parameters and high titered rheumatoid factor of the IgG-IgM-IgA-, IgG-IgA- and IgM patterns. C-reactive proteins were increased more frequently in seropositive cases and correlated quantitatively with the IgG-IgA-, IgG-IgM-, IgG-IgM-IgA and IgA patterns. Maximal erythrocyte sedimentation rates were accompanied with the IgG-IgA-, IgG-IgM-IgA- and IgG-IgM pattern. The serum complement components C 3 and C 4 were not decreased in neither seropositive nor seronegative RA. The formation of antiglobulins in hypergammaglobulinemic patients with RA induced by an increased immunoglobulin catabolism is suggested as a possible pathogenetic mechanism.