Diminished clearance of soluble aggregates of human immunoglobulin G in patients with rheumatoid arthritis

Abstract

Investigation of the capacity of the mononuclear phagocyte system to remove immune complexes from the circulation was performed by the administration of 125I-labelled aggregates of human immunoglobulin G (AIgG) to patients with seropositive rheumatoid arthritis and healthy volunteers. It was found that the rate at which AIgG disappeared from the circulation was significantly prolonged in patients with RA, t1/2 61 +/- 49 min, versus 26 +/- 8 min in healthy volunteers (p less than 0.01). We were not able to establish a correlation between the t1/2 of AIgG and immune complex levels in the circulation, or between t1/2 and articular disease activity (Ritchie index). The sites of removal of AIgG from the circulation were analysed by determining radioactivity levels detectable over liver, spleen and heart. No correlation was found between t1/2 and liver/spleen uptake ratios. We have demonstrated that the removal of AIgG from the circulation of patients with RA is abnormal, though the biological significance of this finding remains to be determined.