COMPOSITION AND BIOLOGICAL BEHAVIOR OF IMMUNE-COMPLEXES ISOLATED FROMSYNOVIAL-FLUID OF PATIENTS WITH JUVENILE RHEUMATOID-ARTHRITIS (JRA)

Data published from in vitro studies have shown that IgM-rheumatoid fa ctor (RF)-bearing immune complexes possess several biological features that may contribute to their pathogenicity. However, no studies have demonstrated that such complexes exist at sites of inflammation in chi ldren with rheumatoid disease. We used two methods of sequential colum n chromatography to purify immune complexes from synovial fluids of ch ildren with JRA. We demonstrate that high molecular weight complexes c ontain IgM-RF, have not bound C4 in vivo, but activate the classical p athway in vitro. In contrast, complexes which have bound C3 in vivo do not contain IgM-RF and are weak complement activators in vitro.