Circulating immune complexes in patients with IgA glomerulonephritis.

Fourty-four patients with IgA-glomerulonephritis (IgA GN) were studied for circulating immune complexes (IC) repeatedly in the course of disease on the evidence of four different methods suited for the detection of IC, viz. complement consumption assay, Clq-solubility test and two tests based on PEG-precipitation, and of indirect signs pointing to the presence of IC. Joint assessment of the direct and indirect signs (positivity of a minimum of 2 indirect signs or any of the direct signs) permitted to ascertain the presence of circulating IC in 72 per cent of the patients and in 63.3 per cent of the examined sera. There was no close relationship between the presence of IC and the clinical activity. On the other hand, in 16 patients positive for the rheumatoid factor (RF) the renal biopsy material revealed extensive vascular lesions. The findings suggest that the circulating IC, some of which contain RF, play a part in the pathomechanism of IgA GN and are involved in the production of the vascular abnormalities in this disease.