title: Enhancement of tumor contrast on radioimmunoscans by using mixtures of monoclonal antibody F(ab')2 fragments.
abstract: F(ab')2 fragments of MAbs GA 73-3 (IgG 2 a) and CO 29.11 (IgG 1), which detect distinct antigenic determinants on adenocarcinoma cells of the gastrointestinal tract, were labeled with 131I using the iodogen method. 41 nude mice bearing SW-948 CRC tumors were injected either with a mixture of 100 microCi (11 micrograms) each (n = 9) of the two 131I-F(ab')2 fragments or with either fragment alone at various doses (each group consisting of 8 mice): GA 73-3, 100 microCi (11 micrograms) and 200 microCi (25 micrograms); CO 29.11, 100 microCi (11 micrograms) and 200 microCi (26 micrograms). Whole-body images of the mice were obtained daily for up to six days after injection. Ratios of cpm/pixel in the tumor to those in the rest of the body (rob), representing tumor contrast, were significantly (p less than 0.05) higher in the group of mice injected with the mixture (3.9 +/- 1.5) as compared to those given 100 or 200 microCi of either fragment separately. The biological half-life (T1/2 biol.) of the mixture (44.7 +/- 14.5 h) in the CRC tumors was significantly (p less than 0.05) longer than T1/2 biol. determined in the groups given either fragment alone. T1/2 biol. in the rob was similar in all groups of mice examined.
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D003110:Colonic Neoplasms / Q000000981:diagnostic imaging*; D006801:Humans; D007140:Immunoglobulin Fab Fragments; D007457:Iodine Radioisotopes; D051379:Mice; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D011877:Radionuclide Imaging; D014183:Transplantation, Heterologous
chemical_list: D000911:Antibodies, Monoclonal; D007140:Immunoglobulin Fab Fragments; D007457:Iodine Radioisotopes