[Clinico-diagnostic significance of rheumatoid factors of different classes in rheumatoid arthritis].

Enzyme immunoassay was used to measure the content of rheumatoid factors (RF) of the M, A, and G classes in the blood sera of 111 patients with rheumatoid arthritis, 30 patients with osteoarthrosis deformans, and 60 donors. The ranges of normal values for each RF class were defined. The levels of all the three RF classes were significantly higher in the patients with rheumatoid arthritis vs. the reference groups. IgM, IgA, and IgG RF were regularly elevated in the patients with rapidly progressing rheumatoid arthritis and with visceritis, whereas IgM and IgG RF levels were increased in those with the maximal activity of the disease. RF of various classes are more often detectable by the enzyme immunoassay than by the Vaaler-Roset's or latex agglutination tests.