It is the purpose of this report to evaluate Thrombin-Antithrombin III Complex (TAT) determination by an ELISA. SDS-PAGE was used to study the thrombin-antithrombin III interaction. In purified systm, when AT-III (1U/ml) was incubated with thrombin (250NIH U/ml), a complex of Molecular Weight (Mol. Wt) 81500 in this electrophoretic system was formed. As time goes by, this band disappeared as a complex of appearent Mol. Wt 78000 was formed. The amount of TAT increased from 4.3±0.23mg/ml to 10.59±0.57mg/ml gradually. In the present of heparin, a complex of Mol. Wt 81500 was formed immediately. As a passage of time, this band disappeared as complex of appearent various low. Mol. Wt were formed and the amount of TAT decreased gradually. From these observations, it was considered that measurable TAT of Mol. Wt 81500 and 78000 were detected in this method. TAT was determinated in plasma from 30 normal subjects, 30 patients with DIC, 15 patients with sepsis, 5 patients with deep vein thrombosis. The results were as follows; normal subjects 2.1±1.2ng/ml (mean±SD), DIC 28.9±43.5ng/ml, sepsis 21.4±11.0ng/ml, deep vein thrombosis 7.6±10.7ng/ml. There did not exist a definite correlation between the levels of TAT and AT-III in patients with these diseases.
In the case of a patient with AT-III deficiency, TAT was markedly elevated and decreased following the infusion of AT-III concentrate and FOY. Heparin cofactor activity decreased and FDP-D dimer increased immediately TAT was elevated. These results indicate that the quantitative assay TAT would be a sensitive parameter for specific detection of the clotting pathway.
