Abstract:

Objective   To detect and compare the expression levels of four IgG subclasses(IgG1、 IgG2、 IgG3 and IgG4)in glomeruli between hepatitis B viral clearance membranous nephropathy (HBV-MN) and idiopathic membranous nephropathy (IMN), and to explore the role of IgG subclasses in the diagnosis and differential diagnosis in nephropathy. Methods   Immunofluorescence was utilized to determine the expressions of IgG1、 IgG2、 IgG3、 IgG4 in kidney biopsy tissues from 32 patients with HBV-MN and 20 patients with IMN. Results   Among the 32 cases of patients with HBV-MN, deposition of IgG1 was identified in 30 cases; IgG4 was positively expressed in 6 cases, and 5 out of these 6 cases were with simultaneous IgG1 deposition; IgG 2 was expressed in 21 cases, and IgG3 was positive in 13 cases. By contrast, deposition of IgG4 was identified in 19 cases with IMN; IgG1 deposition was present in 15 cases, but with weak expression only; Expressions of IgG2 and IgG3 were present in 7 and 4 cases, respectively. Conclusion   IgG1 deposition is mainly present in HBV-MN , but IgG4 deposition is mainly present in IMN, sometimes with IgG1 together.The positive rate between the two groups has no significant difference,but the expression intensity of the HBV-MN group is significantly higher than that of the IMN group. The different patterns of immune complex deposition suggest that the pathogenesis of HBV-MN differs from that of IMN．IgG4 and IgG1 may be the valuable biological indicator in diagnosis and differential diagnosis for IMN and HBV-MN.

Key words: IgG subclass； Idiopathic membranous nephropathy； Hepatitis B virus associated membranous nephropathy