THE PREVALENCE OF RENAL AMYLOIDOSIS OF THE AA‐TYPE IN A SERIES OF 1,158 CONSECUTIVE AUTOPSIES

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Abstract
To determine the prevalence of renal amyloidosis of the AA‐type in a defined population, formalin‐fixed specimens from the kidneys of all the cases autopsied in 1983 at The General Hospital of Malmö, Sweden, were investigated using immunohistochemical techniques. Amyloid deposits of protein AA were found in 10 of 1,158 investigated cases and the calculated prevalence was 0.86 per cent. The mean age at death of the individuals with the AA‐type of amyloidosis was 79 years. Six of the cases with amyloidosis had rheumatoid arthritis. The avidin‐biotin‐peroxidase complex technique was found to be superior to the immunofluorescence method and a high sensitivity and specificity was achieved when sequence‐specific antibodies against a synthetized nonapeptide corresponding to a hydrophilic segment of the polypeptide chain of protein AA were used in the assay. Nine cases with other types of amyloid deposits in the kidneys were also detected. None of these cases showed any AA immunoreactivity but all of them demonstrated Congophilic deposits which were immunohistochemically stained by antibodies against the amyloid P‐component. The prevalence of renal amyloidosis comprising all types of amyloid protein deposits was 1.64 per cent.