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A 75-year-old woman was admitted to our hospital because of proteinuria, pitting edema on the foot, and renal impairment.

Background: We previously reported that idiopathic membranous nephropathy (IMN) strongly correlated with HLA-DRB1*1501-DRB5*0101-DQAI*0102-DQB1* 0602, a specific haplotype of human major histocompatibility complex (MHC), in Japanese patients. To investigate the role of MHC in the development of rat Heymann nephritis (HN), an animal model of membranous nephropathy, a monoclonal antibody (mAb) specific to rat MHC class II antigen (RT1B) was administered, and its effectiveness in inhibiting HN was assessed. Methods: Active HN was induced in HN-sensitive Lewis rats by administering brush border proteins of rat proximal uriniferous tubules (FX1A). Rats were divided into four groups: rats treated with 1,000 µg anti-rat MHC class II mAb, rats treated with 100 µg anti-rat MHC class II mAb, rats treated with murine myeloma IgG, and rats that did not receive either FX1A or any other mAb. We examined the differences in 24-hour urinary protein excretion and serum alloantibody titers against FX1A between groups at different time intervals, and the histologic features of kidneys at the end of the study. Results: HN was induced in Lewis rats by inoculation with FX1A antigen. Administration of anti-MHC class II mAb successfully lowered urinary proteins, production of anti-FX1A alloantibodies, and the development of glomerular lesions in a dose-dependent manner. Conclusion: The present results demonstrated that the MHC class II molecule itself is directly involved in the pathogenesis of HN, and suggest that this therapy would be any better (or less toxic) than nonselective immunosuppressants in the treatment of IMN.

To clarify the relationships between clinical and renal structural findings in non-insulin-dependent diabetes mellitus (NIDDM), we studied 19 renal biopsy specimens from patients with overt diabetic nephropathy induced by NIDDM. By a conventional biopsy examination using light, immunofluorescent and electron microscopy, we excluded patients with any non-diabetic renal diseases which may have caused urinary abnormalities. Using standard stereological methods, the glomerular filtration surface area per nephron (S-Filt/neph), mesangial volume per glomerulus (V-Mes/glom), mesangial matrix volume per glomerulus (V-MM/glom) and the width of the glomerular basement membrane (GBM) were measured in nonoccluded glomeruli. The hyaline change in the arteriole was analyzed semiquantitatively using light microscopy as an index of arteriolar hyalinosis. Light-microscopic findings demonstrated minimal lesions in 4 cases, focal and/or segmental sclerotic lesions in 4 cases, and diffuse mesangial expansion in 11 cases (with and without nodular lesions in 9 and 2 cases, respectively). Mean glomerular volume of an open glomerulus in diabetic patients was 1.6 times the reference value obtained from nondiabetic patients with mild proteinuria and/or hematuria and normal renal function. Clinical parameters, including the duration of diabetes, urinary protein excretion and creatinine clearance were all related to S-Filt/neph, V-Mes/glom, V-MM/glom and the width of the GBM. In addition, V-MM/glom, the width of the GBM and the index of arteriolar hyalinosis were closely interrelated. Based on these findings, diabetic renal changes, including an increase in the mesangial matrix, thickening of the GBM and arteriolar hyalinosis, appeared to progress in parallel, and may reflect various clinical manifestations in patients with overt diabetic nephropathy induced by NIDDM without nondiabetic renal lesions.