Radioimmunolocalization of human gastric carcinoma xenografts SY 86 B and SY 86 D with 131I-labeled monoclonal antibody.

The suitability of individual MAb for application in vivo should be carefully confirmed. The monoclonal antibody GL-013, with specific binding reactivity in vitro to human tumors of the gastrointestinal tract, was radioiodinated and injected intraperitoneally into nude mice bearing human gastric carcinoma xenografts SY 86 B (moderately differentiated glandular adenocarcinoma) and SY 86 D (signet ring cell carcinoma). Whole body scintigraphy indicated tumor localization with 131I-labeled MAb GL-013, but not with 131I-labeled normal mice immunoglobulin. The best tumor contrast was obtained between days 3 and 7 after injection. As confirmation of the imaging results, 131I-GL-013 preferentially localized in tumor tissue compared with normal tissue and 131I-GL-013 gave a higher tumor uptake ratio than the control 131I-NMIgG (at day 9 after injection), as determined by tissue counting of radioactivity. These results demonstrate that MAb GL-013 localizes in xenografts SY 86 B and SY 86 D and the possible clinical application of MAb GL-013 to radioimmunolocalization.