A reproducible model for the study of factor X kinetics in AA amyloidosis

Factor X clearance was examined in a model of rapid AA amyloid deposition. Accelerated equilibration with extravascular compartments and accelerated removal postequilibration mimic features seen in patients with AL amyloidosis. The handling of Factor X was different from that of two other proteins, mouse albumin and IgG. Each protein had its own specific characteristic clearance properties, although in amyloidotic animals all proteins were cleared more rapidly in the postequilibration phase. The liver was by far the major site of Factor X clearance but this was true in all control groups as well. No significant difference was seen in tissue clearance site in any of the treatment groups, perhaps because the amount of AA amyloid in each tissue 3 days into the protocol was not yet large. Nevertheless, a reproducible model that possesses accelerated Factor X clearance is now available to study the mechanism of coagulation factor abnormalities in amyloidosis.