THE LONG-TERM PROGNOSIS OF AA AND AL RENAL AMYLOIDOSIS AND THE PATHOGENESIS OF CHRONIC-RENAL-FAILURE IN RENAL AMYLOIDOSIS

Investigation of the long-term prognosis and pathogenesis of chronic r enal failure in 225 cases of AA and AL renal amyloidosis (perireticula r and perireticular + pericollagenous amyloidosis) yielded the followi ng results: 1) The prognosis of both AA and AL amyloidosis is poor and is worse than all other types of glomerulopathy with the exception of rapidly progressive glomerulonephritis. 2) The probability of maintai ning renal function in AL amyloidosis is no lower than that in AA amyl oidosis. 3) The prognosis of both AA and AL amyloidosis is significant ly worse in cases in which the renal cortical interstitium exhibits fi brosis at the time of the biopsy than in those in which it is normal. 4) In AA and AL amyloidosis, as in various types of inflammatory glome rulopathy, the relative area of the renal cortical interstitium shows a significant positive correlation with the serum creatinine concentra tion and a significant negative correlation with the creatinine cleara nce. However, the extent of interstitial amyloid deposition does not c orrelate with the serum creatinine concentration. Deposition of amyloi d in the renal cortical interstitium has no effect on renal excretory function. 5) The long-term prognosis of renal amyloidosis is related t o the severity of the glomerular amyloidosis in as much as it is gener ally worse in Grades III to V than in Grades I and II. However, it mus t be borne in mind that the incidence of interstitial fibrosis, which is decisive for the long-term prognosis, increases with the severity o f glomerular changes. 6) The long-term prognosis of renal amyloidosis is worse if acute renal failure or interstitial fibrosis is present at the time of the biopsy. Patients with both acute renal failure and in terstitial fibrosis have the worst prognosis. 7) Isolated glomerular a myloidosis, even if there is severe vascular amyloidosis (vas afferens ), does not lead to renal insufficiency or even to a rise in serum cre atinine concentration. 8) The number of T lymphocytes in the tubular e pithelium in AA and AL amyloidosis is significantly greater than norma l, and the number of T lymphocytes, macrophages/monocytes, and fibrobl asts/fibrocytes per unit area of interstitium is also significantly in creased. 9) As far as the pathogenesis of renal cortical interstitial fibrosis in renal amyloidosis is concerned, it is proposed that, in so me cases, this develops from the interstitial edema that is seen in bi opsy specimens of patients with renal amyloidosis and acute renal fail ure. However, it is considered that it more often develops from inters titial inflammation resulting from an autoaggressive response directed against immunoglobulins that have passed through the glomerulus, been reabsorbed by the tubules, and become autoantigens, and against basem ent membrane fragments that act as autoantigens when they pass into th e urine and are then reabsorbed by the tubules.