TUMOR-SPECIFIC ACCUMULATION OF I-125 LABELED MOUSE-HUMAN CHIMERIC ANTI-CEA ANTIBODY IN A XENOGRAFTED HUMAN CANCER MODEL DEMONSTRATED BY WHOLE-BODY AUTORADIOGRAPHY AND IMMUNOSTAINING

Whole-body autoradiography (WEAR) was used to study the biodistributio n of I-125-labeled mouse-human chimeric antibody (Ch F11-39) to carcin oembryonic antigen (CEA) in athymic nude mice bearing the CEA-producin g MKN-45 human gastric carcinoma xenografts. Significantly high uptake of I-125-Ch F11-39 in the tumors obtained by tissue-counting techniqu e was confirmed by WEAR of mice of 12, 24, 48, and 96 h postinjection of I-125 Ch F11-39. When compared with histochemical or immunohistoche mical staining results of the tumor tissue sections, imaging profiles of I-125-Ch F11-39 obtained by WBARs were topographically correlated w ith histopathological findings of tissues and immunohistochemical loca lization of CEA in the tumor tissues, indicating that the accumulation of I-125-Ch F11-39 at the tumor site is based on its specificity for CEA. These results demonstrate that this chimeric antibody may serve a s a potential useful diagnostic and/or therapeutic reagent for human C EA-producing cancers.