Radioimmunolocalization of human brain tumor: fundamental studies with indium-111 labeled monoclonal antibody G-22.

Monoclonal antibody (MCA) G-22 reacts selectively with human glioblastoma. Whole immunoglobulin G (IgG) and the F(ab')2 fragment of G-22 were labeled with indium-111, and injected into athymic nude mice bearing xenografts of a human glioblastoma cell line (U-251-MG). Radiolabeled G-22 retained its antigen-binding activity allowing clear visualization of transplanted tumors. Although the 111In-labeled F(ab')2 fragment had a higher tumor-to-tissue ratio than whole IgG, tumor concentration of 111In-labeled G-22 MCA was higher in the latter and it provided much better images for a longer time when visualized by gamma-scintigraphy. These results suggest that 111In-labeled G-22 may be a useful agent for brain tumor imaging.