Common Immunologic Pathways Between Oligoarticular and Polyarticular Juvenile Idiopathic Arthritis

The polyarticular and oligoarticular forms of juvenile idiopathic arthritis are classified as distinct entities. At the same time, many children who present with an oligoarticular phenotype eventually evolve to a polyarticular disease pattern, suggesting that the phenotypes might share with overlapping molecular mechanisms. Using gene expression microarrays, we found that 14 genes in neutrophils and 55 genes in PBMC shows common patterns of differential expression when children with active oligoarticular and polyarticular JIA were compared with healthy controls. These results demonstrate that there are commonalities between oligoarticular and polyarticular JIA that suggest overlapping immune mechanisms. Total RNA was extracted from isolated PBMC and neutrophils from 14 patients with polyarticular JIA and 8 patients with pauciarticular JIA. Total RNA was extracted from neutrophils from 13 healthy controls and from PBMC from 15 healthy controls. Insufficient RNA for microarrays was obtained from neutrophils from two of the healthy controls.