Tumour localization of radiolabelled monoclonal antibody in mice bearing human urinary bladder (T24) carcinoma xenografts.

: Selectivity of mouse monoclonal antibody 7E9 (IGG3) directed against human urinary bladder carcinoma cells has been examined by indirect membrane immunofluorescence, using a panel of 31 human cell lines. The 7E9 monoclonal antibody discriminated between urinary bladder carcinoma cells and normal urothelium or cells of non-urothelial origin, although occasional reactions with bladder carcinoma-unrelated cell types were observed. The 7E9 antibody was purified by protein A affinity chromatography, labeled with 131I and used for gamma scintigraphy in nude mice xenografted with human urinary bladder carcinoma T24. The 7E9 antibody was capable of locating the T24 xenografts in nude mice; it localized preferentially in the T24 tissue compared to normal mouse tissues. The T24 xenografts could not be detected by gamma scintigraphy with 131I-labelled monoclonal antibody against human mammary carcinoma cells and two other control antibodies. Likewise, the 131I-labelled 7E9 antibody was not capable of locating human mammary carcinoma xenografts in nude mice.