IGG SUBCLASSES IN PATIENTS WITH MEMBRANOPROLIFERATIVE GLOMERULONEPHRITIS, MEMBRANOUS NEPHROPATHY, AND LUPUS NEPHRITIS

Primary glomerulopathy can be classified into seven essential patterns based on histopathological studies. The pathogenesis of membranoproli ferative glomerulonephritis (MPGN), and membranous nephropathy (MN), w hich show glomerular IgG deposition and induce mainely nephrotic syndr ome, is not known. To clarity the role of IgG subclass in glomerulonep hritis, we compared serum concentrations of IgG subclasses, the ratio of serum IgG subclasses to total IgG (%IgG subclass), and glomerular d eposition of IgG subclasses between 7 MPGN patients, 21 MN patients, a nd 9 lupus nephritis (LN) patients. Serum IgG subclasses and %IgG in a ll groups were almost within normal range based on the values in Japan ese healthy adults. In the MPGN and MN groups, the IgG1 concentration was significant lower than that of the LN group (P < 0.001, P < 0.0001 , respectively). The IgG2 concentration in the MPGN group decreased si gnificantly compared with that in the LN group (P < 0.05). The %IgG2 o f the LN group decreased significantly compared with that of the MN gr oup (P < 0.05). The %IgG3 of the MPGN group was significantly higher t han that of the MN group (P < 0.05). The glomerular immunoflourescent intensity of IgG1 and IgG2 were significantly stronger in the LN group than in the MPGN and MN groups (IgG1, P < 0.001, P < 0.01, respective ly; IgG2, P < 0.0001, P < 0.0001, respectively). IgG3 in the MPGN and LN groups deposited significantly compared with that in the MN group ( P < 0.0001, P < 0.01, respectively). The intensity of IgG4 in the MN g roup showed a significant difference compared with that in the MPGN an d LN groups (P < 0.0001, P < 0.01, respectively). IgG3 is an important factor in the pathogenesis of primary MPGN, while IgG4 relates to glo merular IgG deposition in MN.