[Acquired inhibitors to coagulation factors].

Acquired inhibitors (antibodies) to specific coagulation factors develop in certain underlying disorders such as autoimmune diseases, post-partum period and drug reactions. In about half the patients, no underlying diseases are identified. The majority of the patients have a factor VIII inhibitor. The immunological characteristics of the inhibitors revealed them to be IgG4 with restricted polyclonal nature. The inhibitors to factor VIII recognize epitopes of either heavy chain (44 kDa fragment in thrombin activation) or light chain (72 kDa fragment), or both, which correspond to A2 and C2 domains, respectively, both suggested to be functionally important on the factor VIII molecule. In this symposium, we reported the cases with factor VIII inhibitors and factor V inhibitor and the diagnosis and treatment of these diseases. Further analysis of these inhibitors may be helpful in the management of the patients with severe hemorrhage.