Plasma Levels of Unactivated Thrombin Activatable Fibrinolysis Inhibitor (TAFI) Are Down‐Regulated in Young Adult Women: Analysis of a Normal Japanese Population

Abstract

Thrombin‐activatable fibrinolysis inhibitor (TAFI) is an anaphylatoxin‐inactivating enzyme generated by proteolytic cleavage of its zymogen, and is the same enzyme as that first designated by our group as procarboxypeptidase R (proCPR). TAFI in plasma is presumed to influence vascular disease in its role as a fibrinolysis inhibitor. The activity of TAFI is strongly influenced by genetic polymorphism, especially at amino acids Thr/Ala‐147 and Thr/Ile‐325. In this study, we analyzed 202 healthy controls who were not on any medication, had no unusual medical history and whose blood data were normal. In a previous report, we established an enzyme‐linked immunosorbent assay (ELISA) specific for non‐activated TAFI (proCPR), and investigated levels of unactivated TAFI as an estimate of anti‐fibrinolytic capacity. In this study, we determined normal Japanese TAFI levels for each age, sex, and genetic polymorphism of Thr/Ala‐147 and Thr/Ile‐325, and also showed that the TAFI level in young adult women is lower than in aged women.