Complement activation and immune complexes in children with polyarticular juvenile rheumatoid arthritis: A longitudinal study

Objective. To determine whether levels of either circulating immune complexes (IC) or complement activation fragments change as disease activity changes in children with polyarticular juvenile rheumatoid arthritis (JRA). Methods. Twenty-six children with polyarticular JRA were examined over a time course of 4-21 months. Plasma complement activation fragments and IC were measured by commercially available enzyme linked immunoabsorbant assays. Results. Both complement activation fragments and IC levels were lower in individual children when their articular disease was inactive. Children with persistently active disease had no change in any of these measures. Conclusion. Elevated levels of plasma IC and complement activation fragments are features of active polyarticular JRA. We believe our data support a role for the complement system in the pathophysiology of polyarticular JRA.