Recurrence of mesangial deposition of IgA after renal transplantation

摘要

Mesangial deposition of IgA is found in about 20% of adult patients with idiopathic glomerular disease in France. The deposition involves the mesangium of every glomerulus and persists during the whole course of the nephropathy. We therefore believe it to be the hallmark of the disease in these patients [1, 2].Mesangial IgA does not contain secretory piece, and it is usually accompanied by some IgG, IgM has been found by some observers [3, 4], but not by ourselves. C3 is present without Clq or C4 [4, 5], suggesting activation of the complement system by the alternate pathway [6], This is further supported by the demonstration of properdin [4,7]. In our experience, however, the deposition of properdin is much less conspicuous than in acute glomerulonephritis or membranoproliferative glomerulonephritis.By light microscopy, the kidney usually has the appearance of focal proliferative glomerulonephritis but, with thin sections and good trichrome stains, it is often possible to see some fibrinoid deposits in the mesangium of even those glomeruli which show no focal changes. Mild diffuse mesangial hypercellularity is present in some cases, and sometimes the focal changes may be similar to those observed in focal glomerulosclerosis. In advanced cases, interstitial and arteriolar changes become prominent, and without the help of immunofluorescence microscopy, these cases may be misdiagnosed as interstitial nephritis or nephrosclerosis even by experienced pathologists.With the electron microscope, electron-dense deposits are seen in the mesangium of every glomerulus. Silver impregnation may be necessary to clearly distinguish the deposits from the basement membrane and the mesangial matrix. There may sometimes be a slight extension of the deposits to the subendothelial areas. The cytoplasm of mesangial cells is usually richer in organelles than usual but no evidence of phagocytosis of the deposits by these cells can be demonstrated.In adult patients, the disease is usually manifested by light proteinuria and microscopic hematuria. In one-half of the cases, macroscopic hematuria occurs either as a single episode or as recurrent attacks. Gross hematuria is usually precipitated by an upper respiratory tract infection or strenuous exercise. It may be accompanied by loin pain and dysuria. In some patients proteinuria is heavier, and occasionally the nephrotic syndrome may develop. Hematuria and proteinuria may disappear for variable periods of time, but renal biopsy specimens obtained during periods of clinical remission have shown that the mesangial deposits persist.The course of the disease in most adult patients is long-standing but its clinical expression is mild, with little evidence of progression over decades. Nevertheless, hypertension and renal insufficiency may occur. Terminal renal failure eventually develops in about one case in five, and unfortunately we know of no way to predict which patient will follow this course. There is no relationship between the amount of mesangial deposition, which usually remains fairly constant in a given patient, and the severity of the disease.In the child, the mesangial deposition of IgA accounts for about 10% of cases of glomerular disease. It nearly always presents as recurrent hematuria [8,9]; renal tissue often looks normal by light microscopy. The prognosis of recurrent hematuria in children is generally considered to be good, and it is therefore of note that the disease began during childhood in several patients of this report.In most patients, with mesangial deposition of IgA, the serum concentration of IgA is high, but in some patients, it may be normal or even low. The serum concentrations of IgG, IgM and C3 are normal or slightly elevated.There are still no clues as to the etiology of this disease.