Demonstration of amyloid protein AA in old museum specimens.

Three amyloid-infiltrated organs, which had been stored in fixative for 65 to 83 years, were obtained from a collection of pathologic tissues. All the tissues originated from persons with pulmonary tuberculosis. Amyloid fibril protein AA, typical of secondary systemic amyloidosis, was demonstrated in all the tissues by the peroxidase-antiperoxidase method. Protein AA was also extracted and purified from the tissues in spite of the long period in fixative.