[Rheumatoid factors. Isotypes and severity of rheumatoid polyarthritis].

The immuno-enzymatic method permits the separate study of rheumatoid factors (RF): IgM as well as IgG, IgA, IgE, IgD. In 43 patients with rheumatoid polyarthritis (RP), classic or definite, we have studied the correlations between the various parameters of articular and extraarticular activity of RP and the levels of each isotype of RF. A statistically significant correlation of the articular activity was found with RF IgG (p less than 0.01), RF IgA (p less than 0.01). As compared to RP without rheumatoid nodule, RPs with rheumatoid nodules presented a level of RF IgM (p less than 0.05), RF IgG, IgA, IgE (p less than 0.01) which was statistically higher; a statistically significant correlation was found between haptoglobin levels and those of RF IgG (p less than 0.01). A negative correlation, statistically significant, was found between CH 50 and the levels of RF IgM. This study confirms previous studies which were carried out with an immuno-enzymatic method of detection of RF isotypes.