[Antineutrophil cytoplasmic autoantibodies in children: clinical features]

Antineutrophil cytoplasmic antibodies (ANCA) are usually considered as serological markers of vasculitis (microscopic polyangiitis, granulomatosis with polyangiitis, and Churg-Strauss syndrome), but they have also been described in other diseases. They are rarely observed in children. Therefore, this study aims to describe the clinical spectrum associated with positive ANCA in children.

All the children below 15 years of age, admitted to the Angers University Hospital between June 2004 and June 2010 presenting with an ANCA-positive test by indirect immunofluorescence were included in this study. The exhaustive list of ANCA-positive children was obtained from the immunology unit. Six antigenic targets were routinely tested by Elisa, i.e., proteinase 3, myeloperoxidase, bactericidal permeability increasing protein, cathepsin G, elastase, and lactoferrin. Clinical and biological data were retrospectively collected.

Thirty-seven children were identified with positive ANCA in this 6-year period. None of the antigenic targets tested was found in 21 patients. The most frequent diseases associated were inflammatory bowel disease (n=10), infections (n=6), hematological disease (n=5), and juvenile idiopathic arthritis (JIA) (n=4). Patients with JIA presented with a predominance of antielastase antibodies.

In contrast to the findings usually observed in adults, we obtained a wide spectrum of clinical entities associated with positive ANCA in this cohort. In children, the ANCA test has 2 advantages: to diagnose systemic vasculitis and to differentiate inflammatory bowel disease. Patients with JIA seemed to have more frequent antielastase antibodies: in the future, this finding should be further investigated in larger prospective studies.