Urinary detection of type IV collagen and its increase in glomerulonephritis.

Type IV collagen is the major component of the glomerular extracellular matrix. The nature of type IV collagen antigens in the urine from various forms of glomerulonephritis was studied using enzyme-linked immunosorbent assay for monoclonal antibodies to the 7S domain and some of the non-7S and non-NC1 domains. The size distribution of antigenic material in urinary samples from a patient with IgA nephropathy was analyzed by gel filtration chromatography. The results demonstrated a single peak at 340 kDa, suggesting the measurement of almost intact type IV collagen molecules. The urinary concentration of type IV collagen in patients with membranous nephropathy and chronic renal failure was significantly increased compared with that of normal controls. Measurement of the urinary concentrations of type IV collagen is useful in the diagnosis of glomerular disease, particularly in cases where invasive methods are contraindicated and clinically membranous nephropathy is suspected.