Antineutrophil cytoplasmic antibodies in juvenile chronic arthritis

To evaluate the diagnostic significance of antineutrophil cytoplasmic antibodies (ANCA) by assessing the prevalence of ANCA in juvenile chronic arthritis (JCA) (n = 93) of either oligoarticular, polyarticular, 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 connective tissue diseases.

Indirect immunofluorescence on both ethanol and paraformaldehyde fixed neutrophils, ELISA for specific antigens, Western blotting using sonicated neutrophils.

ANCA were detected in the sera from 35% of patients with JCA, and in only 7% of patients with other inflammatory diseases. Regarding the onset type of JCA, ANCA were present in 44% of patients with oligoarticular onset, in 36% with polyarticular onset, and in 16% with systemic onset. All but one ANCA positive serum sample produced a perinuclear fluorescence pattern on ethanol fixed granulocytes. However, on neutrophils fixed with paraformaldehyde either a cytoplasmic (14%) or a nuclear (23%) staining pattern was observed, suggesting that both cytoplasmic and nuclear 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 reactivity with either lactoferrin (5%) or 2 polypeptides of 66/67 kDa (9%).

Prevalence and antigenic specificity of ANCA in JCA are clearly different from adult onset rheumatoid arthritis or other juvenile chronic inflammatory disorders.