[The difference between rheumatoid factors and normal immunoglobulins disclosed by a monomolecular layer technic]

20 rheumatoid factors of two classes, namely IgG and IgM, were isolated from the serum of 11 patients with rheumatoid arthritis. The method of monolayer analysis revealed that these proteins differ from normal ones either by the instability of their native structure, or by their anomalous hydrophilic properties. Dialysis resulted in partial or complete restoration of normal properties in the majority of samples studied. It has been concluded that at least some of the rheumatoid factors are complex structures that contain, beside IgG and IgM molecules, also certain smaller molecules.