The incidence of immunoglobulin-A deposits in glomerular diseases and its morphological examination: nephropathy with mesangial IgA dense deposits.

The presence of IgA with IgG, C', IgM and fibrin in 365 renal biopsy specimens has been studied by the immunohistological method. Glomerular IgA deposits were found in 38 cases (10.4%). The patients were divided into two groups according to the localization of IgA: 13 cases (3.56%) belonged to the first group, in which IgA showed diffuse mesangial localization. Light microscopic examination showed various stages of proliferative glomerulonephritis. These cases corresponded to the nephropathy described by Berger. In 25 cases (6.85%), belonging to the second group, the glomerular localization of IgA was found to be segmental and peripheral, appeared always in patches and was present with various histological alterations. Differentiation of the two kinds of alteration is possible primarily on the basis of the immunohistological pattern, but light microscopic and electron microscopic examination might also be helpful.