Solubilization of immune complex deposits by native 7S IgG molecules in lupus glomerulonephritis--a possible antigen excess effect on rheumatoid factor-IgG complexes.

IgM and IgG class rheumatoid factor (RF) containing glomerular immune complex (IC) deposits were detected in renal biopsy material from 10 out of 123 patients with various forms of glomerulonephritis (GN) by an immunofluorescent assay using FITC conjugated aggregated human IgG(FAHIgG). In lupus GN, six out of 28 cases (23.5%), showed such activity. Solubilization of glomerular IC deposits in frozen sections of lupus GN was observed after a 5 h incubation with native 7S IgG. The binding of FAHIgG to glomerular IC deposits and solubilization of deposits by excess HIgG were also confirmed in sections of two types of rat experimental GN in which HIgG acted as exogenous antigen; in situ IC formation type GN in cationized HIgG planted kidneys and chronic serum sickness type GN. These results suggest a possible antigen excess mechanism contributing to the solubilization of glomerular IC deposits via RF and IgG interactions in lupus GN.