FACTOR-V INHIBITOR ASSOCIATED WITH SJOGRENS-SYNDROME

We report an unusual case of a 74-year-old male who developed a serum autoantibody reactive with human coagulation factor V (FV) in an activ ated form, as demonstrated by coagulation studies and immunoblotting a nalysis. Despite marked prolongation of a prothrombin time and an acti vated partial thromboplastin time in this patient, the inhibitor was n ot associated with clinical bleeding but with multiple cerebral infarc tions. The patient had suffered from Sjogren's syndrome with polyclona l hypergammaglobulinaemia. The patient's purified IgG, an immediately acting inhibitor to FV, reacted with a light chain of thrombin-activat ed FV (FVa) and inhibited the procoagulant activity of FVa without aff ecting the cleavage of FVa by activated protein C. The FV inhibitor ma y arise from activation of FV with consequent exposure of neoantigen d uring the activation of coagulation cascade in the patient with an aut oimmune disorder for the background.