Abstract

We describe a 72-year-old man, who had been suffered from Henoch-Schönlein purpura (HSP) several times, presented with hematoproteinuria with granular cast, and general lymphadenopathy. The immunological examination of the serum showed polyclonal hypergammagloburinemia with high value of IgG4. The renal biopsy revealed interstitial inflammatory cell infiltration, including infiltration of lymphocytes and plasma cells, and segmental glomerulonephritis. Direct immunofluorescence microscopy revealed apparent positive staining with anti-human IgA, and anti-human IgG in glomeruli, anti-human IgG4 antibody staining showed many positive plasma cells in the interstitium. The patient was diagnosed with HSP nephritis that was complicated by IgG4-related nephropathy. As a result of the treatment with 30mg prednisolone, the swelling of the LNs decreased, but the patient continued to have persistent hematoproteinuria.

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.

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