Specific biodetection of B16 mouse melanoma in vivo by syngeneic monoclonal antibody.

The specific detection of tumors in vivo using a radiolabeled syngeneic monoclonal antibody made by fusion of P3U1 (BALB/c myeloma cells) and C57BL/6 spleen cells primed with syngeneic B16 melanoma cells was investigated by color imaging, autoradiography, and biodistribution. The radiolabeled antimelanoma antibody specifically accumulated only in the tumor lesions, whereas no radioactivity was observed in normal tissues or organs. The distribution patterns of the radioactive antibody in the tumor lesions depended on the sizes of the tumor. Almost the entire region of the small metastatic tumor in lymph nodes was labeled, whereas the radioactive antibody was irregularly localized mainly in the center of the medium-sized tumor. However, only the peripheral region of the large primary tumor was labeled. The highest uptake of radioactivity (tumor:blood ratio) was observed in the small lymph node metastatic tumor lesions rather than in the large primary tumor. Furthermore, high resolution color imaging of B16 melanoma was also obtained by using 125I-labeled monoclonal antibody. Tumor location was specifically visible without subtraction or enhancement methods 3-5 days after injection of the radiolabeled antibody.