Glomerular basement membrane thickening in renal allografts.

Diffuse thickening of glomerular basement membranes (GBM) was optically observed in the renal grafts of 15 patients (21 specimens) among 70 recipients (128 specimens). Most of these specimens with diffuse GBM thickening were examined ultrastructurally. All cases with the above change were only found in allografts. The correlation was observed between the degree of GBM thickening and the clinical course. which can be classified into 3 groups. Group I showed a marked thickening of subendothelial spaces of GBM due to the accumulation of electron-lucent material. The cases of Group I fell into renal failure within relatively sWort periods because of either continued or repeated acute rejections (4 cases at 10 weeks to 15 months after transplantation). Group II showed a relatively mild thickening of subendothelial spaces and mild thickening oflaminae densae accompanied by chronic rejections (7 cases at 9 months to 10 years and 10 months after transplantation). Group III showed glomerulonephritis-like changes and chronic clinical courses (3 cases with membranoproliferative glomerulonephritis (MPGN)-like change and one case with membranous nephropathy (MN)-like change). The GBM thickening was milder in Group II than in Group I. Mesangiolysis was found in both groups, which was, however, milder in Group II. The one case with MN-like change in Group III was considered to be complicated with MN under chronic rejection. As to the 3 cases with MPGN-like changes in Group Ill, it can not be concluded at a preset, whether they are to be attributed to a special form of chronic rejection itself or to a chronic rejection on which glomerulonephritis or some other factor(s) may be superimposed.