Comparative study of two methods of 99m Tc-lablled anti-CEA monoclonal Antibodies with nude mice radioinmunoimaging.

Purpose To evaluate the effect of two methods of 99mTc Anti - CEA monoclonal Antibodies with nude mice radiommunoimaging. Methods Labeled anti - CEA antibodies with fresh 99mTc,2 - mercaptoethanol (2 - ME) and 2 - iminohiolane (2 - IT) method was used respectively. Labeling rate and radiochemical purity were determined, and anti - CEA nude mice imaging were obtained. Results The highest radioimmunoac-tivity of labeling anti - CEA with 2 - ME was 69.1 % , the labeling rate was 88.7% and colloid content was 8.1% , whereas in 2 - IT method were 73.2% ,93.7%and 4.8% respectively. The radiochemical pruity were all above 90% at 2h,4h,6h and 24h after labeling. The stability of 2 - IT-method was better than that of 2 - ME method. The labeling time expanded and method used had their own characteristics. The radiommunoimaging showed significant radioactiviey in tumor ratio of 2 - IT and 2 - ME was 3.44 ± 0.61 and 2.92 ± 0.89 respectively. The radioactivity of blood pool, liver and kidney seems much less in mice of 2 - ME method by observation. Conclusion The pre-treatment methods of 2 - ME and 2 - IT could both satisfy the conjugation of hydrosulfide group, and also labeled 99mTc effectively with less protein injruy and simple in procedure. the Tc labeling anti - CEA antibodies had high affinity with tumor, and was suitable for radioimmunoimaging, among them the method of 2 - IT had higher labeling rate, less colloid conten, higher T/NT ratio and more stable, thereby it seemed that much more suitable for radioimmunoimaging.