Immunohistologic features of minimal-change nephrotic syndrome.

To assess the role of immune mechanisms in the pathogenesis of minimal-change nephrotic syndrome (MCNS), immunohistologic studies were performed on renal biopsy specimens from 31 patients. Glomerular immunoglobulin and/or complement (C3) deposition was present in 20 specimens. Deposits were usually minimal to moderate, granular, and focal in nature. IgM was present in 17 specimens, C3 in 10, IgG in 8 and IgA in only 3. With a mean follow-up of 5 1/2 years, there is no difference in the response to therapy of patients with no glomerular immunoglobulin or C3, those with glomerular immunoglobulin without C3, and those with glomerular C3. These findings indicate that glomerular immune deposits can be seen in a substantial percentage of patients with MCNS, but the minimal and focal nature of the deposits and lack of correlation with response to therapy suggest that immunoglobulin and C3 deposits are nonspecific and have no pathogenetic role.