Acquired circulating anticoagulants in children with acquired immunodeficiency syndrome

The mechanism underlying the prolonged activated partial thromboplastin time (APTT) seen in some pediatric patients with acquired immunodeficiency syndrome (AIDS) and opportunistic infections was studied. A circulating inhibitor of coagulation was demonstrated in three patients. The inhibitor appears to be an immunoglobulin that interferes with some of the phospholipid-dependent coagulation reactions of the intrinsic pathway. This 'AIDS anticoagulant' does not predispose the patient to clinical bleeding despite its ability to cause a marked prolongation of the APTT. As such, careful laboratory diagnosis of the cause of abnormal coagulation test results is necessary for children with AIDS.