[Immune complexes and C3 and C4 of the complement in urine of patients with glomerulonephritis].

The circulating immune complexes (CIC), urinary immune complexes (UIC), C3 and C4 in urine (UC3 and UC4) in 99 patients with immunologic glomerular diseases: 13 with extracapillaris GN (ExGN), 38 with membranoproliferative GN (MPGN), 33 with mesangial proliferative GN (MesPGN), 5 with focal segmental glomerulosclerosis (FSGS), 5 with membranous nephropathy (MN), and 3 with minimal change nephropathy (MC) were investigated in the study. Depending on the (IS) immunosuppressive treatment all patients were classified into 3 groups. Group I: 61 recently biopsied patients with glomerular disease consisted of patients attending our renal department, group II: 24 patients with biopsy proven glomerular disease IS treated in the past but with GN with restrained disease activity, group III: 14 patients with active glomerulopathy who have been treated for some months. Nephelometry C1q binding test was used for CIC detection and 3.5% polyethylene glycol precipitate for its detection in urine by C1q binding test was applied. Radial immunodiffusion (NANORID) method was used for urine C3 and C4 detection. UC3 were detected in urine from 37% of all patients: in 39% patients of group I (GN at time of diagnosis), 38% of group II (GN with restrained disease activity) and 36% of group III (active GN received immunosuppressive therapy for several months). It suggest that nonimmunological-mechanism induce C3 detected in the rine of such patients. According to histological findings UC3 was detected in 3 patients with ExGN of group I, in patient with ExGN of group II and in about half patients with MPGN from group I and II, in about 25% patients with MesPGN from group I and II. About half patients with MesPGN of group III, one patient with MPGN of group III and a few patients with other histological findings of group I were UC3 positive. Simultaneous excretion of C4 in urine was detected in some UC3 positive patients (in about 5% patients). At the same time in about 50% UC3 positive patients was observed urinary excretion of IC. CIC and UIC were detected in 25% of all patients: in 29% of group I, in 17% of group II, and in 29% patients of group III. According to histological findings CIC was detected in 3 patients with ExGN, in 7 patients with MPGN from 26 of group I, and 3 from 7 with MPGN of group II, and 3 patients with MesPGN of group I and 1 patients with MesPGN of group II, and 33% patients with MesPGN of group III with high proteinuria. These findings suggested that urinary IC reflected the immunological activity of glomerulopathy and their presence in patients urine after IS treatment suggests incomplete response to this therapy while urinary C3 and C4 were connected with urinary protein excretion and may be of importance in tubulointerstitial injury and progression of renal insufficiency.