Detection of IgM rheumatoid factors by enzyme-linked immunosorbent assay in children with juvenile rheumatoid arthritis: correlation with articular disease and laboratory abnormalities.

This study was undertaken to determine the clinical relevance of IgM rheumatoid factors (RFs) detected by enzyme-linked immunosorbent assay (ELISA) in children with juvenile rheumatoid arthritis (JRA) by examining their association with severity of acute articular disease. ELISAs for IgM-RF were performed on serum specimens from 65 children with JRA. Activity of articular disease was estimated by an arbitrary scoring system. Significant differences were seen in articular disease activity between the group of children with polyarticular disease who were IgM-RF-positive by ELISA compared with those who were IgM-RF-negative (P = .0003). When a small group of individual children with polyarticular disease were followed longitudinally, similar correlations were found between severity of acute disease and the presence of IgM-RFs detected by ELISA. In children with pauciarticular JRA, expression of IgM-RFs appeared to be a transient phenomenon with no correlation with either articular disease or laboratory abnormalities.