PREPARATION AND BIOLOGICAL EVALUATION OF RADIOLABELED ANTIBODIES WITHSELECTED CARBOHYDRATE MODIFICATIONS

Two carbohydrates, N-acetylgalactosamine (GalNAc) and galactose-beta-1 ,3-GalNAc have been attached to human IgG (hIgG) by a novel linking re agent, hexafluoroglutaric acid dimethyl ester. Fluorine-19 NMR signals were used for the determination of the conjugation ratio. A third car bohydrate, sialic acid, was conjugated via reductive amination and the conjugation ratio determined by a resorcinol assay. The biological be haviour of these radioiodinated antibodies with carbohydrate modificat ion in normal mice indicates an enhanced liver uptake at 15 min post-i njection with an associated change in circulating blood levels occurs for the galactose-based hIgG preparations. However, no significant dif ferences in the biodistribution were observed for the sialic acid conj ugate. These studies confirm the potential of carbohydrate-antibody co njugation for modifying the behaviour of antibodies in immunoscintigra phy and radioimmunotherapy.