Circulating immune complexes in glomerulonephritis: a longitudinal study

A longitudinal study of circulating immune complexes (CIC) was performed in 121 patients with biopsy verified glomerulonephritis (GN). 1286 blood samples were obtained during a mean observation period of 21 months. Two methods for detection of CIC were used, the Clq-binding activity and a PEG precipitation test. CIC were detected by both tests in 21% of all blood samples and detected in at least one blood sample from 57 patients. The presence of CIC was found to be either transient (34 patients), intermittent (11 patients) or permanent (12 patients). CIC were found transiently at the time of renal biopsy and disappeared within months in patients with idiopathic extracapillary GN (7 of 9 patients), endocapillary GN (2/2) and GN associated with polyarteritis nodosa (5/6), Wegener's granulomatosis (3/3) and Henoch-Schoenlein syndrome (3/6). CIC were detected either transiently, intermittently or permanently for years after renal biopsy in patients with SLE (12/14) and membranoproliferative GN type I (7/12). CIC were only occasionally detected in patients with minor change nephropathy (1/9), membranoproliferative GN type II (0/2), IgA nephropathy (6/17), focal segmental sclerosis (1/8) and membranous GN (2/11). In these patients CIC were often transiently present without apparent relationship to time since renal biopsy. Overall, a relationship was found between the presence of CIC and decreasing serum creatinine, but there was no correlation with changes in proteinuria or with increasing blood pressure. Serial measurements of CIC showed correlations with clinical events only in individual patients, but not in the population as a whole.