FATE OF SUBEPITHELIAL DEPOSITS IN ACUTE POSTSTREPTOCOCCAL GLOMERULONEPHRITIS

Abstract

The resolution of subepithelial deposits was studied by EM in 17 biopsies from 5 patients (mean follow-up 2.8 yr) with clinically and histologically resolving acute poststreptococcal glomerulonephritis. The electron-dense subepithelial deposits were present in biopsies obtained .ltoreq. 45 days after onset. By 30-45 days after onset, the dense deposits decreased in number, and electron-lucent subepithelial deposits (areas suggestive of foci where deposits were recently resorbed) and lucent deposits covered by a layer of lamina densa-like material (intramembranous deposits) appeared. Some of the subepithelial dense deposits were apparently completely resolved, some were resolving and some were transformed into intramembranous deposits. The resolution appeared to take place both from a continuous loss of EM invisible components of deposited material and through a removal of larger fragments of the deposits by epithelial vesicles. The intramembranous deposits persisted in all but 1 patient during the entire follow-up. Membranous changes, although mild and segmental, apparently develop regularly in acute poststreptococcal glomerulonephritis and constitute a normal phase in the resolution of the subepithelial deposits. The absence of progressive membranous changes in these patients can probably be attributed to the short time during which immune complexes are deposited in the glomeruli.