“Inhibitor Like” Effects of Hematoporphyrin on Factor VIII (Antihaemophilic Globulin)

Abstract

SummaryThe incubation of factor VIII with HP resulted in a progressive loss of factor VIII activity which was dependent on the porphyrin concentration. The rate of reaction was retarded by fibrinogen and glyoxaline, but was not accelerated by reduction in fibrinogen concentration. No increase in factor VIII activity was found when fibrinogen was added after destruction of factor VIII by HP, suggesting irreversibility of factor VIII destruction. The reaction was light but not temperature dependent; in other respects it closely resembled the kinetics observed during factor VIII destruction by naturally occurring anticoagulants and antibody inhibitors of factor VIII.