The analysis of gastrointestinal amyloidosis in 78 patients with chronic renal failure

Systemic amyloidosis is not a single disease, but the product of a variety of diseases. Amyloid proteins are insoluble fibrils that are deposited extr acellularly in many organ tissues. They stain wit Congo red and appear appl e green under polarized light. Definitive diagnosis and classification of a myloidosis requires histologic examination of tissue samples. Gastrointesti nal tract involvement is common, and all parts of the system can be affecte d. Immunohistochemical studies have shown that amyloid deposited in the gas trointestinal system is most often of the AA, A kappa, or A lambda types. A nother type of amyloid protein, beta-2 microglobulin (beta 2M), predominant ly affects the musculoskeletal system, and is usually seen in patients who have been on long-term hemodialysis. Mixed systemic amyloidosis (beta 2M an d AA) is seen only rarely in these patients. In this study, we attempted to answer why this is so,and examined whether or not mixed amyloidosis is rel ated to amyloidogenesis. We studied gastrointestinal tissues from 78 chronic renal failure patients who had systemic amyloidosis with gastrointestinal involvement. A total of 115 endoscopic samples and 1 jejunal resection specimen were analysed immun ohistochemically. Immunohistochemical testing using a panel of antisera dir ected against two major amyloid fibril proteins (AA-Monoclonal, Dako-, and beta 2M- Polyclonal, Dako-) showed that all samples contained AA amyloid, b ut not beta 2M type protein. These findings can be explained by the patient s' relatively short average duration of hemodialysis and the predominance o f endoscopic biopsy samples in our study.