[Studies on the mechanism of glomerular localization of immune complexes (2). Localization of non-dissociable immune complexes on the subepithelial side of the glomerular basement membrane].

In order to investigate whether preformed (circulating) immune complexes (IC) can localize in the subepithelial side of the glomerular basement membrane (GBM), non-dissociable covalently cross-linked IC (cov. IC) composed of native ferritin (NF) and anti NF antibody (aNFab) were preformed in a 2 step reaction using the bifunctional reagent, toluene-2,4-diisocyanate (TDI). Molecular weight of cov. IC was about 58 x 10(4) dalton, which suggests that the cov. IC was composed of Ag1Ab1 lattices. The GBM of mice given cov. IC intravenously showed that deposition of cov. IC was not only in the lamina rara interna but also, with time, in the lamina densa and lamina rara externa. The size of cov. IC and the distribution in the GBM described above were similar to those we studied previously using preformed dissociable NF and aNFab complexes in a 40-fold antigen great excess. From these results, we concluded that preformed immune complex in vitro can pass through the lamina densa as intact IC to give rise to the subepithelial area without dissociation or reformation. That is, the subepithelial IC deposits arise from the trapping of small-sized IC derived from the circulation.