Methods of detection of factor XIa and tissue factor

A method of detecting Factor XIa (FXIa) in a test sample from a subject suffering from or suspected of suffering from at least one of inflammation, acute coronary syndrome (ACS), myocardial infarction, coronary artery disease (CAD), heart failure, aortic stenosis, stroke, or transient ischemic attack comprising:

• a) contacting the test sample with a contact pathway coagulation inhibitor that does not inhibit FXIa;
• b) contacting a portion of the contact pathway coagulation inhibited test sample with a FXIa specific antibody under conditions to permit binding of the antibody to FXIa;
• c) contacting the antibody treated test sample with Ca++ and a phospholipid surface;
• d) detecting clotting time of the antibody treated test sample relative a reference portion of the contact pathway coagulation inhibited test sample not contacted with antibody;
• and
• e) correlating a prolongation of clotting time of the antibody treated portion of the test sample relative to the reference portion of the sample with inflammation, acute coronary syndrome (ACS), myocardial infarction, coronary artery disease (CAD), heart failure, aortic stenosis, stroke, or transient ischemic attack in the subject.