Tissue Localisation of Four Monoclonal Anti-CEA Antibodies in a Colon Tumour Xenograft

Abstract Four monoclonal anti-CEA antibodies, 1C12, MA/200, 1B1 and H58, have been compared for their ability to localise a human adenocarcinoma grafted in nude mice. Using the paired labelling method for specific and non-specific immunoglobulins all antibodies showed specific localisation in tumours (specificity index 1.6-3.4 after 7 days). Antibodies 1C12 and MA/200 showed the highest uptake by the tumour 3.4 and 2.1 mean % injected dose/gm respectively) with low tissue/blood ratios for the reference organs. In contrast, 1B1 and H58 showed poor tumour uptake and 1B1 was not retained by the tumour. Both of these antibodies showed an unusually high accumulation in the liver and spleen. Binding affinity and NCA-1 cross-reactivity of antibodies appear to be unimportant for localising the tumour in this model.