Summary
A further modification of Merskey’s hemagglutination inhibition assay for measurement
of fibrinogen degradation products (FDP) in human serum was developed. Blood is clotted
in the presence of protamine chloride (25 u/ml), in addition to thrombin and s-aminocaproic
acid, and at room temperature. Defibrination is complete within 5 min even in blood
obtained from patients on heparin treatment. The hemagglutination immunoassay was
also considerably accelerated by immediate addition of sensitized red cells to the
mixtures of antiserum and antigen dilutions at 37° C. Accurate readings of FDP titers
may thus be obtained within 20 min following venipuncture.