Validation of in vivo receptor measurements via in vitro radioassay: technetium-99m-galactosyl-neoglycoalbumin as prototype model

J Nucl Med. 1991 Jun;32(6):1177-82.

Abstract

Hepatic binding protein (HBP) is a hepatocyte-specific receptor for serum asialoglycoproteins. The receptor also recognizes a synthetic glycoprotein that has been developed as a radiopharmaceutical, technetium-99m-galactosyl-neoglycoalbumin (99mTc-NGA). This report describes the correlation between receptor parameters measured in vivo via kinetic modeling of 99mTc-NGA and those measured by in vitro radioassay of biopsied liver tissue. Eleven patients with diffuse hepatic disease underwent percutaneous liver biopsy followed by a 99mTc-NGA functional imaging study. In vivo measurements of HBP quantity Ro and forward binding rate constant kb obtained from the kinetic analysis of 99mTc-NGA liver and blood time-activity data were compared to total receptor quantity and the HBP-99mTc-NGA association constant KA as measured by Scatchard binding assay of the biopsied tissue. The correlation coefficients between in vivo and in vitro measurements were 0.73 (df = 8, p = 0.015) and 0.98 (df = 8, p less than 0.01) for Ro and kb, respectively. The in vivo measurements of HBP biochemistry via kinetic analysis of the radiopharmaceutical time-activity data reflect the average concentration and affinity of the receptor. This study further substantiates the validity of 99mTc-NGA as a quantitative probe for the HBP receptor.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Aged
  • Albumins*
  • Asialoglycoprotein Receptor*
  • Biopsy
  • Carrier Proteins / metabolism*
  • Female
  • Humans
  • Liver / pathology*
  • Liver Diseases / diagnostic imaging*
  • Liver Diseases / pathology
  • Male
  • Middle Aged
  • Organotechnetium Compounds*
  • Platelet Glycoprotein GPIb-IX Complex*
  • Platelet Membrane Glycoproteins*
  • Radionuclide Imaging
  • Receptors, Immunologic / metabolism*

Substances

  • Albumins
  • Asialoglycoprotein Receptor
  • Carrier Proteins
  • Organotechnetium Compounds
  • Platelet Glycoprotein GPIb-IX Complex
  • Platelet Membrane Glycoproteins
  • Receptors, Immunologic
  • glycoprotein receptor GPIb-IX
  • hepatic sialoglycoprotein receptor
  • technetium Tc 99m neogalactoalbumin