Prevalence of IgM-, IgA- and IgG-rheumatoid factors in seronegative polyarticular disease compared to pauciarticular disease in juvenile chronic arthritis as measured by ELISA.

OBJECTIVE: To determine the prevalence of the rheumatoid factor isotypes measured by enzyme-linked immunosorbent assay (ELISA) in polyarticular and pauciarticular juvenile chronic arthritis (JCA), and evaluate the diagnostic test qualities. PATIENTS AND METHODS: 53 patients with JCA (20 with seronegative polyarticular disease at onset, 21 with pauciarticular onset and course of disease and 12 with extended pauciarticular disease), as well as 125 control children (58 healthy controls and 67 patients with other diseases) were tested. ELISA for the detection of IgM-, IgA- and IgG-isotypes of RFs was used. The diagnostic characteristics of the tests were evaluated by means of clinical epidemiology methods. RESULTS: The prevalence of the ELISA for IgG-, IgA-, and IgM-RF for JCA patients vs all controls at optimal cut-off titres was 13%, 29%, and 32%, respectively. The test for IgG-RF was established to be of no significance. IgA-RF had higher prevalence in the polyarticular and extended pauciarticular form, 40% and 33%, respectively. IgM-RF showed a prevalence of 55% for the polyarticular and 42% for the extended pauciarticular form. No significant prevalence has been found in the pauciarticular form. CONCLUSION: Our results indicate that ELISA for IgG-RF is of no diagnostic value for JCA. The ELISAs for IgM- and IgA-RFs demonstrated a diagnostic significance for the polyarticular and extended pauciarticular form. Juvenile chronic arthritis (JCA) is a heterogeneous disease which encompasses different forms defined by the type of onset. There is evidence, supported by immunogenetic studies that the various subgroups may represent distinct disease entities [1, 2]. Numerous immunological abnormalities have been detected in JCA, but the most characteristic serological findings are ANA and IgM-rheumatoid factor, thought to be useful in the classification of patients and their management. Antinuclear antibodies are universal in JCA, most commonly found in children with early onset pauciarthritis and late onset seropositive polyarthritis [1, 2, 3]. In contrast, the IgM-rheumatoid factor, measured by conventional agglutination techniques, is a hallmark only of polyarthritis with late onset resembling adult rheumatoid arthritis. This group of patients with "seropositive" disease represents less than 20% of all JCA children. Of those patients with "seronegative" disease 20-30% have a systemic onset and the remainder have either a pauciarticular or polyarticular form [2, 3]. Following the introduction of more sensitive techniques, it has already been established that rheumatoid arthritis (RA) patients' sera contain not only the "classical" 19S IgM-RF, but also other isotypes of the rheumatoid factor (RF). A number of studies have emphasized the presence of IgG-, IgA-, IgM- and even IgE- RF in patients with "seronegative" RA [4, 5, 6]. The aim of this study is to determine the prevalence of IgG, IgM and IgA RFs and to attempt at evaluating the diagnostic and prognostic qualities of the ELISA-tests for rheumatoid factor isotypes in polyarticular and pauciarticular forms at onset of JCA.

Sulphasalazine. An alternative drug for second-line treatment of juvenile chronic arthritis.

Sulphasalazine has been established to be an effective drug for second line treatment of early mild to moderate rheumatoid arthritis. Its application for juvenile chronic arthritis (JCA) is limited so far and controversial results for the efficacy of this therapy have been published. We studied the efficacy and tolerance of the sulphasalazine treatment in 32 patients with JCA (10 with polyarthritis, 21 with pauciarthritis and 1 with systemic form). Our results revealed significant response of the treatment at the end of the 6th month in 24/31 patients (77%). In one patient the treatment was discontinued because of transitory neutropenia at the end of the 1st month. No significant difference was observed between the efficacy of the treatment in the polyarticular and pauciarticular disease, as well as newly-diagnosed cases and those with longstanding disease. From the group of 17 children treated up to the end of the 1st year 88% achieved complete remission. No serious toxic effects were observed, with the exception of two cases with transitory low-grade neutropenia. According to our results sulphasalazine is an effective and well tolerated drug for second line treatment of JCA-patients.