To determine whether children with extended oligoarticular juvenile idiopathic arthritis (JIA) produce less of the anti-inflammatory cytokine interleukin-10 (IL-10) than those with persistent oligoarticular JIA.
We measured IL-10 production in the parents of children with oligoarticular or extended oligoarticular JIA, from whole-blood cultures stimulated with lipopolysaccharide.
IL-10 production was lower in the parents of children with extended oligoarticular JIA compared with those of children with oligoarticular JIA (P=0.034). There was an increase in the percentage of ATA-containing genotypes (i.e. genotypes ATA/ATA, ATA/ACC or ATA/GCC) in the parents of children with extended oligoarticular JIA compared with healthy controls (P<0.02) but not in the parents of children with oligoarticular JIA.
As approximately 84% of the variation in IL-10 production is thought to be genetically regulated, these results suggest that stimulated IL-10 production would be lower in children with extended oligoarticular JIA. Because IL-10 is an anti-inflammatory cytokine, this may partly explain why this group of children has more severe disease.