Biodistribution study of murine monoclonal anti-GD3 antibody in nude mice bearing human melanoma xenografts for development of immunoscintigraphy.

Reactivity of the monoclonal antibody with the tumor markers is known to be different between cultured cells in vitro and transplanted tumors in vivo. The monoclonal antibody should be investigated regarding its specific accumulation in tumor-bearing mice for immunodetection or immunotherapy. We studied the biodistribution of radiolabeled monoclonal anti-GD3 antibody (IgM) in normal mice and nude mice bearing human melanoma xenografts. Tissue-to-blood distribution ratios of the antibody in the liver, spleen and kidney increased with time in both normal and melanoma-transplanted mice, but no significant changes were observed in other normal tissues up to 5 days after injection. Specific accumulation of the monoclonal anti-GD3 antibody in the grafted human melanoma (HMV-II) was observed 4 and 5 days after injection. On the other hand, no specific accumulation of standard murine IgM in the tissue of HMV-II was observed in mice bearing the HMV-II xenograft 5 days after injection. Because the tissue-to-blood ratio of the distribution in the tissue of HMV-II became larger than that of other tissues 4 and 5 days after administration, 4 days after the administration of the monoclonal anti-GD3 antibody were required for immunoscintigraphy. Accumulation of the monoclonal anti-GD3 antibody in other human melanomas (HMV-I, HMY-1 and SK-MEL188) inoculated into mice was also observed 4 days after the antibody administration. The monoclonal anti-GD3 antibody used in this study would be useful in immunodetection or immunotherapy.