The distribution of type I collagen in normal and diseased renal tissues was studied using immunofluorescence and immunoelectron microscopy, and was compared with that of type III collagen. In normal human kidneys, a monoclonal antibody against type I or type III collagen reacted with the renal interstitium, but not with the intra-glomerular structures. In various types of glomerulonephritis, immunofluorescent staining for type I collagen was positive in the fibrocellular and fibrous crescents, sclerosed glomeruli, and infrequently within the glomerular mesangium. In the crescents and sclerosed glomeruli, type I collagen was co-localized with type III collagen. The staining intensity of type I collagen in those areas was generally stronger than that in the interstitium. Mesangial staining for type I collagen was present within the glomeruli, particularly with a marked mesangial matrix increase, but was less in amount and frequency compared with type III collagen staining. These findings indicate that the fibrosclerotic process in damaged glomeruli is accompanied by the appearance of interstitial collagens, and that participation of type I collagen is prominent in crescent organization and global glomerular sclerosis, but is less frequent in mesangial expansion, compared with type III collagen.

Kidney specimens taken from normal humans and patients with various renal diseases were examined by immunofluorescent and immunoelectron microscopy using a monoclonal antibody to the alpha 1 chain of type III collagen. Indirect immunofluorescent staining revealed that intraglomerular localization of type III collagen antigen in 41 of 66 patients, while it was absent from the glomeruli of normal human kidneys. Type III collagen was found within the mesangium of 22 patients with various types of renal diseases, and was distributed in a focal and segmental manner in most of the cases. Mesangial localization of the collagen correlated with the increase in the mesangial matrix. Type III collagen was also present in the vascular pole, crescents (particularly in the organizing phase) and sclerosed glomeruli. Immunoelectron microscopy using pre-embedding and post-embedding techniques confirmed the above observations. These findings indicate that type III collagen participates in mesangial expansion, crescent organization, and glomerulosclerosis.

Immunoelectron microscopy was used to localize membrane attack complex (MAC) and hepatitis B e (HBe) antigen in renal tissue specimens from a total of 9 patients with membranous nephropathy (MN); 6 with MN associated with a hepatitis B virus (HBV) infection, 2 with idiopathic MN, and 1 with lupus nephritis. All the patients were proteinuric, and 2 patients were classified as stage I-II, 6 as stage II, and 1 as stage IV. MAC, along with IgG and C3, was distributed within the subepithelial electron dense deposits in all the stages. MAC was also stained in the striated membranous structures within the glomerular basement membrane and mesangial matrix of some patients. In HBV-associated MN, HBe antigen was localized in the subepithelial electron dense deposits of 5 patients, while it was absent from the subepithelial deposits in a patient that was sero-positive for hepatitis B s antigen but negative for HBe antigen. This patient also lacked MAC deposition in these loci. These results suggest that MAC is associated with the formation of subepithelial deposits and proteinuria in MN. In HBV-associated MN, HBe antigen-antibody immune complex makes up the subepithelial deposits and is likely to activate the terminal components of complement in situ.