Method for measuring blood procoagulant activity of human leukocyte antigens

摘要

Thromboembolic complications have been documented in cancer patients and mismatched organ transplant recipients. Procoagulants have been implicated in these processes and may play an additional role in tumor metastases. Two proteins displaying procoagulant activity, with molecular weights of 35,000 and 28,000 daltons, were isolated from human ovarian carcinoma extracts. The amino terminal sequence of the first 12 amino acids of the 35,000 dalton protein was determined to be IKEEHVIIQAEF. This sequence displays 100% homology to the major histocompatibility (MHC) antigen HLA-DR which exists as an heterodimer composed of a 35 kDa and 28 kDa protein. The procoagulant activity was further purified through immunoaffinity column chromatography involving a monoclonal antibody to HLA-DR. The immunoaffinity purified protein enhanced thrombin generation in recalcified normal plasma approximately 20-fold. HLA-DR procoagulant activity was completely abrogated by the addition of Staphylcoccal aureus enterotoxin A (SEA).