Acquired circulating anticoagulant with anti-factor V activity in AIDS: first case report.

An acquired circulating anticoagulant with anti-factor V activity appeared in a 29 year old AIDS patient with widespread Kaposi's sarcoma following 21 days of fresh frozen plasma therapy for haemolytic and uraemic syndrome. Residual factor V activity was very low (< 5% of normal). However, the inhibitor was of low titre (0.5 Bethesda Units/ml), while antigenic factor V levels remained at 100%. Dot blotting with human factor V and polyvalent and specific immunoglobulin antisera showed the antibody to belong to the IgG class. Haemostatic tests in vitro were only partly corrected by addition of washed human platelets and despite transfusion of large amounts of platelets the patient died from massive pulmonary haemorrhage. This would appear to be the first documented case of an anti-factor V inhibitor occurring in an AIDS patient.