The pathogenesis, clinical course, and response to treatment in systemic juvenile idiopathic arthritis (SJIA) differ from other types of juvenile idiopathic arthritis and are similar to other interleukin-1 (IL-1)-mediated diseases.
Interaction between HLA-DR and HLA-DP, and between HLA and interleukin 1 alpha in juvenile rheumatoid arthritis indicates heterogeneity of pathogenic mechanisms of the disease.