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 renal failure in 225 cases of AA and AL renal amyloidosis (perireticular and perireticular + pericollagenous amyloidosis) yielded the following 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 maintaining renal function in AL amyloidosis is no lower than that in AA amyloidosis. 3) The prognosis of both AA and AL amyloidosis is significantly worse in cases in which the renal cortical interstitium exhibits fibrosis 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 glomerulopathy, the relative area of the renal cortical interstitium shows a significant positive correlation with the serum creatinine concentration and a significant negative correlation with the creatinine clearance. However, the extent of interstitial amyloid deposition does not correlate with the serum creatinine concentration. Deposition of amyloid in the renal cortical interstitium has no effect on renal excretory function. 5) The long-term prognosis of renal amyloidosis is related to the severity of the glomerular amyloidosis in as much as it is generally worse in Grades III to V than in Grades I and II. However, it must be borne in mind that the incidence of interstitial fibrosis, which is decisive for the long-term prognosis, increases with the severity of 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 interstitial fibrosis have the worst prognosis. 7) Isolated glomerular amyloidosis, even if there is severe vascular amyloidosis (vas afferens), does not lead to renal insufficiency or even to a rise in serum creatinine concentration. 8) The number of T lymphocytes in the tubular epithelium in AA and AL amyloidosis is significantly greater than normal, and the number of T lymphocytes, macrophages/monocytes, and fibroblasts/fibrocytes per unit area of interstitium is also significantly increased. 9) As far as the pathogenesis of renal cortical interstitial fibrosis in renal amyloidosis is concerned, it is proposed that, in some cases, this develops from the interstitial edema that is seen in biopsy specimens of patients with renal amyloidosis and acute renal failure. However, it is considered that it more often develops from interstitial 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 basement membrane fragments that act as autoantigens when they pass into the urine and are then reabsorbed by the tubules.