Immunohistologic Study of Chronic Diffuse Prolif erative Glomerulonephritis

Abstract

Distribution in the glomerular tufts of IgG, A, M, β₁C/β₁A, globulin and fibriongen was immunologically investigated in 46 renal biopsy specimens. The subjects were 23 cases of chronic diffuse proliferative glomerulonephritis, 14 cases with minimal glomerular changes (6 cases of mild glomerulonephritis, 6 cases of orthostatic proteinuria and 2 cases of minimal change nephrosis), 4 cases of membranous nephropathy and 5 cases of SLE nephritis. The results obtained were as follows. (1) In membranous nephropathy and SLE nephritis IgG was the major component of the deposit, while small amount of other kinds of Ig was found occasionally. In membranous nephropathy there were cases with additional deposition of IgM. In SLE nephritis IgA and M were found in all cases as accessory components. (2) Chronic proliferative glomerulonephritis: (a) IgG was found in the glomerular deposits in 8 cases, IgA in 20 cases, IgM in 19 cases. Coexistence of IgG, A, and M was seen in 8 cases, IgA and M in 8 cases. IgA alone was deposited in 4 cases and IgM alone in 3 cases. When the cases were classifiod into G, A and M types according to the dominant Ig component, 16 cases belong to A type, 6 cases to M type and only 1 case to G type. (b) The deposits along basement membranes of glomerular tufts ware, except in one case of lobular glomerulonephritis, discontinuously distributed and variously shaped-fine granular, linear, crescent-like or lumpy. So they are different from the grenular, continous deposits observed in membranous nephropaty and in many cases of SLE nephritis and also from the deposits reported in acute post-streptococcal glomerulonephritis. (c) Definite deposition into mesangium was observed in 7 cases with glomerular changes of higher grade. Five cases belonged to A type, 1 case to G type and 1 case to M type. (d) The case of lobular glomerulonephritis described above was the only case of chronic proliferative glomerulonephritis, that showed granular deposits of G type along basement membrane and diffuse deposition of Ig of the same type into mesangium. It suggests that lobular glomerulonephritis belongs, immunohistologically, to acute glomerulonephritis, and that the deposition of A type and M type is characteristic to chronic proliferative glomerulonephritis. (e) The cases of A type had from mild to severe proteinuria and nearly good renal function. Histologically, IgA was assumed to be less active in causing mesangial cell proliferation than IgG, though it does not always assure favorable of the cases of A type. (f) Out of 6 cases of M type, 4 cases showed renal insufficiency and 2 cases were suffering from nephrotic syndrome. The former cases had long duration of the illness from 4 to 9 years, and showed, light-microscopically, widespread sclerosing changes and fibrinoid necrosis of glomerular capillaries. Histologically, mesangium infiltrated by IgM showed as mild mesangial cell proliferation as in the case of IgA. The immunological state of these patients was compared with " dysimmune " state (Okabayashi) observed'd in the end stage of prolonged sensitization with egg albumin or bovine serum globulin.(g) Judging from the amount of urinary protein, the activity to injury basement membrane was thought to be nearly the same among IgG, A and M. Relation was found between the amount of deposition of IgA along basement membrane and the grades of proteinuria.(3) In the cases with light-microscopically minimal glomerular changes, mild deposition of fine granular or linear materials was found along basement membrane in all of 6 cases of mild glomerulonephritis, in 2 of 6 cases of orthostatic proteinuria and in one of 2 cases of nephrotic syndrome. The dominant Ig was G in one case, A in 6 cases and M in one case.(4) Ths results of the present study indicate that immunohistological study, especially directed to IgG, . A and M, is essential to the clinico-pathologic study of chroic diffuse proli