A quantitative method for detecting deposits of amyloid A protein in aspirated fat tissue of patients with arthritis

Objective-To describe a new, quantitative, and reproducible method for detecting deposits of amyloid A protein in aspirated fat tissue and to compare it with smears stained with Congo red.Methods-After extraction of at least 30 mg of abdominal fat tissue in guanidine, the amyloid A protein concentration was measured by a monoclonal antibody-based sandwich ELISA.Results-The concentrations in 24 patients with arthritis and AA amyloidosis (median 236, range 1.1-8530 nglmg tissue) were higher (pConclusion-This is a new, quantitative, and reproducible method for detecting deposits of amyloid A protein in aspirated fat tissue of patients with arthritis, even when minute deposits are present as detected in smears stained with Congo red.