FACTOR VIIA AND OTHER HEMOSTATIC VARIABLES FOLLOWING BONE-MARROW TRANSPLANTATION

Hepatic venocclusive disease causes considerable morbidity and mortali ty following bone marrow transplantation. There are two hypotheses reg arding the aetiology of this syndrome; firstly that changes in plasma coagulation factors and natural anticoagulants lead to a prothrombotic state and secondly that endothelial cell activation stimulates intrav ascular deposition of fibrin. We have investigated these mechanisms by measuring the changes in proteins C and S and factors VII and X in th e post transplant period and by using the plasma concentration of fact or VIIa as an in vivo marker of potential endothelial cell tissue fact or expression. Protein C fell in both allograft and autograft patients but more so in the allografts. Similar results were found for factors VII and X. These changes were predominantly due to hepatic dysfunctio n induced by the chemo-radiotherapy. Factor VIIa levels were unchanged in both the allograft and autograft patients. We conclude that there is no convincing evidence for a procoagulant state following BMT as th ere are both anticoagulant and procoagulant changes. The absence of an y changes in factor Wa levels suggests that tissue factor was not expo sed to the general circulation following BMT but does not exclude foca l expression at the sites of thrombosis.