Sera from 66 children with active JCA of oligoarticular, polyarticular or systemic onset, 13 sera from patients in disease remission, 15 sera from patients with reactive arthritis, and 11 from Lyme arthritis patients were tested for the presence of anti-neutrophil cytoplasmic antibodies (ANCA) in order to evaluate their diagnostic significance in JCA.
ANCA were found in 21% (14/66) of the active JCA sera, all showing an atypical pANCA staining pattern using indirect immunofluorescence on ethanol fixed granulocytes. 71% of these sera also showed antinuclear antibodies (ANA) on HEp-2 cells. By additional staining on paraformaldehyde fixed granulocytes to exclude staining artefacts due to ethanol fixation, 2 of the pANCA positive sera showed cytoplasmic staining. In no case did we find nuclear fluorescence suggesting a true cytoplasmic localization of the involved antigens. All ANCA positive sera were negative for anti-MPO and anti-LF antibodies. ANCA prevalence in our study group did not correlate with the disease subgroup, disease duration or other clinical characteristics. However, we found ANCA only in active disease.
Our data suggest that the diagnostic importance of ANCA in JCA is restricted to only a few JCA patients. In these cases, however, ANCA positivity supports the diagnosis of JCA. Further studies are needed to substantiate this finding, as well as possible subgroup specificities. Standardized techniques of granulocyte fixation and antigen specific tests are needed to produce comparable results in different study groups.