DETERMINATION OF PLASMA TISSUE FACTOR ANTIGEN AND ITS CLINICAL-SIGNIFICANCE

To investigate the clinical significance of determination of plasma ti ssue factor (TF) antigen, we have developed a highly sensitive enzyme- linked immunosorbent assay (ELISA) for plasma TF, using two different monoclonal antibodies against TF apoprotein, 6B4 (catching antibody) a nd 5G9 (detecting antibody), and tetramethyl benzidine/H2O2 as substra tes. Titration curves of recombinant human TF in buffer containing Tri ton X-100 were linear within the range from 50 to 2000 pg/ml. The tota l assay time was 3 h. Ultracentrifugation and immunoblot analysis indi cated that human plasma and urine contained 50000 g sedimentable and n on-sedimentable forms of TF, both of which were detected by our ELISA method. Plasma and urine concentrations of TF in healthy subjects and patients with various diseases were measured by the ELISA method. In h ealthy subjects, plasma and urinary TF levels were found to be 149 +/- 72 pg/ml (n = 30) and 175 +/- 60 pg TF/urine creatinine mg (n = 95), respectively. TF was increased in plasma of patients with disseminated intravascular coagulation (DIC), thrombotic thrombocytopenic purpura, vasculitis associated with collagen diseases, diabetic microangiopath y and chronic renal failure receiving haemodialysis, but not in the pl asma of endotoxaemic patients without DIC. The plasma TF/serum creatin ine ratio did not show a positive correlation. Measurement of TF antig en in plasma may be useful for evaluating the endothelial damage and c ell destruction in TF-containing tissues.