Comparison of the biodistribution of 75Se- and 131I-labelled monoclonal antibodies in nude mice

Abstract

A monoclonal antibody, C-215, against colon cancer, was internally labelled with [⁷⁵Se]methionine. The biodistribution was studied in tumour-bearing nude mice and compared with the biodistribution of [¹³¹I]C-215. The tissue uptake was divided into three parts: antibody bound to the antigen, antibody in the extracellular space and uptake of the released radionuclide. [⁷⁵Se]C-215 showed a greater amount of antigen-bound antibody in the tumour, but also a greater unspecific uptake both in tumour and normal tissue.