title: Fluorine-18 labeling of monoclonal antibodies and fragments with preservation of immunoreactivity.
abstract: A new method is reported for labeling proteins with the positron-emitting nuclide 18F. Initially, 4-[18F]-fluorobenzylamine was prepared in two steps from aqueous [18F]fluoride in high yield. The 18F acylation agent was formed by reaction of this product with disuccinimidyl suberate. Overall yields for the 4-[18F]fluorobenzylamine succinimidyl ester ([18F]SFBS), decay corrected to the end of cyclotron bombardment, were about 30% in a synthesis time of 60 min. After a 15-min reaction, 30-45% (decay corrected) of the [18F]SFBS could be coupled to intact antibodies and their F(ab')2 and Fab fragments. Coupling yields were dependent on protein concentration but not reaction time. HPLC purification of [18F]SFBS was necessary to obtain optimal coupling efficiency and immunoreactivity. The immunoreactivities of 18F-labeled F(ab')2 and Fab fragments of an antimyosin antibody were 89 +/- 5% and 75 +/- 9%, respectively. Biodistribution studies in normal mice demonstrated similar in vivo behavior of 18F-labeled antibody fragments and those labeled with 125I by using N-succinimidyl 3-[125I]iodobenzoate. These results indicate that this method may be useful for labeling monoclonal antibodies and other proteins and peptides with 18F.
authors.affiliation: Duke University Medical Center, Department of Radiology, Durham, North Carolina 27710.
authors.forename: P K
authors.initials: PK
authors.lastname: Garg
authors.forename: S
authors.initials: S
authors.lastname: Garg
authors.forename: M R
authors.initials: MR
authors.lastname: Zalutsky
mesh_terms: D000107:Acetylation; D000818:Animals; D000911:Antibodies, Monoclonal / Q000493:pharmacokinetics / Q000494:pharmacology*; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D005462:Fluorine Radioisotopes / Q000493:pharmacokinetics; D007128:Immunoglobulin Fragments / Q000493:pharmacokinetics / Q000494:pharmacology*; D007553:Isotope Labeling / Q000379:methods*; D051379:Mice; D008807:Mice, Inbred BALB C; D013388:Succinimides / Q000737:chemistry / Q000302:isolation & purification / Q000493:pharmacokinetics / Q000494:pharmacology; D014018:Tissue Distribution
chemical_list: D000911:Antibodies, Monoclonal; D005462:Fluorine Radioisotopes; D007128:Immunoglobulin Fragments; D013388:Succinimides; C069226:N-succinimidyl 8-((4'-fluorobenzyl)amino)suberate