title: Radiolabeling antibodies with holmium-166.
abstract: We report the preliminary results from radiolabeling of a chelate-conjugated antibody with 166Ho produced from the beta(-)-decay of 166Dy. Ho-166 was separated from mg quantities of Dy target by reverse phase ion-exchange chromatography employing a cation exchange HPLC column and 0.085 M alpha-HIBA at pH = 4.3 as eluent. Evaporation to dryness of 166Ho fraction (up to 25 mL) and thermal decomposition of alpha-HIBA yielded 166Ho in a dry state which was then solubilized in 0.5 mL of 0.1 M HCl. Subsequent radiolabeling of CHX-B-DTPA conjugated 135-14 monoclonal antibodies with purified 166 Ho was readily achieved with approximately 80% efficiency and with a specific activity of 3-4 mCi of 166Ho per mg of protein. 166Ho-antibody conjugates are stable with regards to transferrin challenge for a period of 50 h. Further, it was shown that any Fe3+ ions present in alpha-HIBA as an impurity interfere with the labeling.
authors.affiliation: Nuclear Medicine Group, Oak Ridge National Laboratory (ORNL), TN 37831-6229, USA.
authors.forename: E
authors.initials: E
authors.lastname: Dadachova
authors.forename: S
authors.initials: S
authors.lastname: Mirzadeh
authors.forename: S V
authors.initials: SV
authors.lastname: Smith
authors.forename: F F
authors.initials: FF
authors.lastname: Knapp
authors.forename: E L
authors.initials: EL
authors.lastname: Hetherington
mesh_terms: D000911:Antibodies, Monoclonal / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004419:Dysprosium / Q000737:chemistry; D006695:Holmium / Q000737:chemistry*; D006885:Hydroxybutyrates; D018796:Immunoconjugates / Q000737:chemistry*; D007553:Isotope Labeling / Q000379:methods; D004369:Pentetic Acid / Q000138:chemical synthesis; D011868:Radioisotopes / Q000737:chemistry*
chemical_list: D000911:Antibodies, Monoclonal; D006885:Hydroxybutyrates; D018796:Immunoconjugates; D011868:Radioisotopes; D004419:Dysprosium; D004369:Pentetic Acid; C008039:2-hydroxyisobutyric acid; D006695:Holmium