Protein Z: a new coagulation inhibitor involved in several pathologies

Abstract

Protein Z (PZ) is a vitamin-K dependent factor isolated from human plasma in 1987. Its structure is near to that of other proteins of coa-gulation vitamin-K dependents. Its physiological role had been unrecognized for a long time but it was established that the protein Z act as a cofactor of an inhibitor dependent of PZ (ZPI). The latter is also synthesized by liver and was purified from human plasma in 1998. The PZ/ZPI complex inhibe direct-ly the factor Xa.
An increase of PZ was observed in pregnancy, and inflammation such as lym-phoma, rheumatoid arthritis and haemodialysis.
The level of PZ is markedly low in liver disease, the use of vitamin-K anta-gonist and oral contraception, the patients with nephrotic syndrome and patients with malignant tumors.Several studies reported conflicting results on the role of PZ in venous and arterial thrombosis. Low PZ levels were observed in patients with antiphos-pholipid syndrome. It was reported a high frequency of PZ deficiency in woman with unexplained primary early foetal losses and early foetal death. Consequently PZ level should be performed in the etiologic check up for unexplained foetal losses.