title: Biotin delivery to brain with a covalent conjugate of avidin and a monoclonal antibody to the transferrin receptor.
abstract: The OX26 mouse monoclonal antibody to the rat transferrin receptor undergoes transcytosis through the brain capillary endothelial wall, which makes up the blood-brain barrier (BBB) in vivo, owing to high concentrations of transferrin receptor on the BBB. This property allows the OX26 antibody to serve as a brain drug transport vector. To simplify coupling of therapeutics to the OX26 antibody, the present studies examine the use of the avidin/biotin system to promote coupling of biotin and biotinylated drugs to brain transport vectors. The OX26 antibody was affinity purified from ascites fluid and was covalently coupled via a thioether linkage to avidin, and the conjugate was purified to homogeneity by gel filtration fast protein liquid chromatography. The biotin binding capacity of the avidin-OX26 conjugate was measured, and 2.3 biotin binding sites per avidin-OX26 (1:1) conjugate were detected. Transcytosis through the BBB of [3H]biotin bound to either unconjugated avidin or to the avidin-OX26 conjugate was measured with an internal carotid artery perfusion/capillary depletion technique. [3H]Biotin bound to the avidin-OX26 conjugate was transported through the BBB at rates that equaled the rate of transcytosis of the unconjugated OX26 antibody. The clearance from plasma of [3H]biotin bound to the avidin-OX26 conjugate approximated the rate of clearance of the unconjugated OX26 antibody, and not the rate of clearance of [3H]biotin bound to avidin, which was cleared from plasma at much faster rates.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Medicine, UCLA School of Medicine.
authors.forename: T
authors.initials: T
authors.lastname: Yoshikawa
authors.forename: W M
authors.initials: WM
authors.lastname: Pardridge
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000008:administration & dosage* / Q000737:chemistry; D001360:Avidin / Q000008:administration & dosage* / Q000737:chemistry / Q000493:pharmacokinetics; D001710:Biotin / Q000008:administration & dosage* / Q000737:chemistry / Q000493:pharmacokinetics; D001812:Blood-Brain Barrier; D001923:Brain Chemistry; D004337:Drug Carriers / Q000493:pharmacokinetics; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D011990:Receptors, Transferrin / Q000276:immunology*; D014018:Tissue Distribution
chemical_list: D000911:Antibodies, Monoclonal; D004337:Drug Carriers; D011990:Receptors, Transferrin; D001360:Avidin; D001710:Biotin