ANTINEUTROPHIL CYTOPLASMIC ANTIBODIES IN JUVENILE CHRONIC ARTHRITIS

Objective, To evaluate the diagnostic significance of antineutrophil c ytoplasmic antibodies (ANCA) by assessing the prevalence of ANCA in ju venile chronic arthritis (JCA) (n = 93) of either oligoarticular, poly articular, or systemic onset. To investigate the prevalence of ANCA in other diseases of childhood characterized by chronic inflammation (n = 44), such as cystic fibrosis, juvenile diabetes mellitus, and connec tive tissue diseases. Methods, Indirect immunofluorescence on bath eth anol and paraformaldehyde fixed neutrophils, ELISA for specific antige ns, Western blotting using sonicated neutrophils. Results, ANCA were d etected in the sera from 35% of patients with JCA, and in only 7% of p atients with other inflammatory diseases. Regarding the onset type of JCA, ANCA were present in 44% of patients with oligoarticular onset, i n 36% with polyarticular onset, and in 16% with systemic onset. All bu t one ANCA positive serum sample produced a perinuclear fluorescence p attern on ethanol fixed granulocytes. However, on neutrophils fixed wi th paraformaldehyde either a cytoplasmic (14%) or a nuclear (23%) stai ning pattern was observed, suggesting that both cytoplasmic and nuclea r autoantibodies occur in JCA. Further characterization studies showed that ANCA in JCA are not directed against proteinase 3, elastase, or myeloperoxidase. On Western blots ANCA in JCA incidentally showed reac tivity with either lactoferrin (5%) or 2 polypeptides of 66/67 kDa (9% ). Conclusion, Prevalence and antigenic specificity of ANCA in JCA are clearly different from adult onset rheumatoid arthritis or other juve nile chronic inflammatory disorders.