A group of 40 subjects (33 women and 7 men) assembled in the course of several years comprised clinical and ambulatory patients. The main characteristic of the group was isolated seropositivity of rheumatoid factors assessed by the latex fixation test with titres of 1:320 and more in apparently healthy subjects. The mean age of the subjects at the beginning of the investigation was 39 years. They were followed up for 2-18 years, on average for 7.8 years. Regular clinical, biochemical and immunological check-up examinations were made after 1-2 year intervals. The latex fixation test was made in a test tube. The most serious manifestation was the development of rheumatoid arthritis in 7 subjects (6 women and 1 man). In two of them it was preceded by palindromic rheumatism. Two women have abortive manifestations of systemic lupus erythematosus. Seven developed, mostly repeatedly, tendovaginitis in the region of the flexors of the fingers and abductors of the thumb. Seven subjects suffered from polyarthritis of the hands. None of the subjects suffered from cirrhosis or monoclonal gammapathy. In the course of the investigation the titres of rheumatoid factors had a declining trend even to negative values. In 23 they became negative or had titres of 1:40. The high incidence of rheumatoid arthritis in 17% apparently healthy subjects with isolated seropositivity of rheumatoid factors emphasizes the importance of dispensarization of these subjects in a rheumatological surgery and of careful long-term follow up. Early administration of line 2 antirheumatic drugs could prevent a possible fatal course of rheumatoid arthritis.

Keywords: Adult; Aged; Arthritis, Rheumatoid /immunology/; Female; Follow-Up Studies; Humans; Latex Fixation Tests; Male; Middle Aged; Rheumatoid Factor /blood/