Demonstration of Apoptosis-associated Cleavage Products of DNA, Complement Activation Products SC5b-9 and C3d/dg, and Immune Complexes CIC-C3d, CIC-IgA, and CIC-IgG in the Urine of Patients with Membranous Glomerulonephritis

Aim: To investigate the involvement of complement activation and apoptosis in the pathogenesis of membranous glomerulonephritis by determining the concentrations of apoptosis-associated 180 bp nucleosomes and complement activation products SC5b-9 and C3d/dg in the urine of patients with membranous glomerulonephritis.

Methods: Morning urine was taken from 15 patients with immunohistologically established membranous glomerulonephritis. Apoptosis-associated 180 bp nucleosomes, complement activation products SC5b-9, C3d/dg, and immune complexes CIC-C3d, CIC-IgA, and CIC-IgG were detected in the urine samples by using antigen-specific enzyme-linked immunosorbent assay.

Results: Concentrations of measured parameters were expressed in units of standard deviation, ie, relatively to the average concentrations measured in healthy subjects. We found drastically increased concentrations of apoptosis-associated 180 bp nucleosomes (13.71+/-14.97; p=0.047), complement activation products SC5b-9 (197.07+/-134.88; p=0.003) and C3d/dg (38.70+/-43.35; p=0.048), and immune complexes CIC-C3d (11.01+/-13.39; p=0.74), CIC-IgA (7.93+/-4.38; p=0.001), and CIC-IgG (20.56+/-10.87; p=0.001) in the urine of patients with an active form of membranous glomerulonephritis. All studied molecules were absent, or present in very low concentrations, in healthy subjects and patients with membranous glomerulonephritis in remission. The mean differences between healthy controls and patients with the active disease were statistically significant in all parameters, except CIC-C3d.

Conclusions: There is an association of complement activation and apoptosis with membranous glomerulonephritis. Correlation analysis suggests that the excretion of apoptosis-associated 180 bp nucleosomes, SC5b-9, C3d/dg, and immune complexes containing IgA and IgG in the urine of patients with active membranous glomerulonephritis does not depend solely on the passive transport together with other proteins, but is probably an independent active process.