ANTIFIBRIN MONOCLONAL-ANTIBODIES FOR THE DETECTION OF VENOUS THROMBOSIS

In order to specifically detect the localization of thrombus in vivo, we have recently developed two monoclonal antibodies (SZ-58, SZ-63) wh ich can specifically bind to cross-linked fibrin. The binding rates of the two monoclonal antibodies (MoAbs) to human plasma clots in vitro were 46.4 +/- 2.3% for I-125-SZ-58, 50.1 +/- 1.7% for I-125-SZ-63 and 3.4 +/- 1.6% for I-125-SZ-53 (control, MoAb against TM). It was shown that both SZ-58 and SZ-63 posess properties of inhibiting the polymeri zation of fibrin, and SZ-58 could also inhibit the aggregation of plat elets induced by ADP. These characteristics make the two MoAbs suitabl e in the detection of thrombus in vivo. According to the cross reactio n tests, thrombi in the jugular veins and carotid arteries in rabbits were made. After injection of the I-125-labeled MoAbs (100 000 cpm/ml of blood), the thrombi and the blood were taken and weighed at various time intervals and radioactivities were measured by an autogamma coun ter. The ratios of thrombus to blood radioactivity (T/B) of thrombi in jugular veins were 3.0, 5.6 and 3.0 for I-125-SZ-58, 1.5, 3.0 and 5.2 for I-125-SZ-63 and 1.2, 1.0 and 0.7 for control (I-125 -SZ-53) at th e 3rd, 12th and 24th hour after the injection of the radiolabled MoAbs , while the radioactivities of arterial thrombi were almost the same a s that in blood after the injection of the two radiotracers. Therefore , it can be concluded that both SZ-58 and SZ-63 can be used in venous thrombus imaging in vivo and the optimal times of imaging are at the 1 2th hour for SZ-58, 24th,hour for SZ-63 after the injection of the rad iolabled MoAbs.