Indium-111 labeled monoclonal antibodies (Ab): The effect of DTPA conjugation on the Ab activity and tissue distribution
Monoclonal antibodies (Ab) to human ..cap alpha..-fetoprotein (AFP) were conjugated with diethylenetriaminepentaacetic acid (DTPA) using cyclic DTPA anhydride and the obtained conjugates, DTPA-Ab, were labeled with In-111. The effect of DTPA conjugation on the affinity constant and the maximum binding capacity of Ab was evaluated by radioimmunoassay and Scatchard plot analysis and In-111 labeled DTPA-Ab were used for the radioimmunodetection of tumor. Ab containing 1.0 DTPA molecule per Ab showed almost full retention of both the affinity constant and the maximum binding capacity. Then, 40 ..mu..Ci of In-111 labeled DTPA-Ab were injected intravenously to nude mice bearing AFP-producing human testicular tumor and the resulted were compared with I-131 labeled Ab. Scintigraphy clearly revealed transplanted tumor. Localization of In-111 labeled DTPA-Ab was significantly higher than I-131 labeled Ab. Tumor to blood ratio obtained at 4 days after injection was 2.59 with In-111 labeled DTPA-Ab compared to 0.99 with I-131 labeled Ab. When more than 1.9 DTPA molecules were incorporated per Ab, the maximum binding capacity decreased, although the affinity constant was less affected. These In-111 labeled DTPA-Ab caused significantly higher liver accumulation. These results indicate that In-111 labeled DTPA-Ab at a cojugated DTPA to Ab molar ratio of 1.0 may be superior to I-131 labeled Ab for tumor imaging, but the maximum binding capacity and tissue distribution of In-111 labeled DTPA-AB are greatly dependent upon the number of DTPA molecules incorporated per Ab molecule.
- Research Organization:
- Kyoto Univ., Kyoto
- OSTI ID:
- 7089623
- Report Number(s):
- CONF-840619-
- Journal Information:
- J. Nucl. Med.; (United States), Journal Name: J. Nucl. Med.; (United States) Vol. 25:5; ISSN JNMEA
- Country of Publication:
- United States
- Language:
- English
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62 RADIOLOGY AND NUCLEAR MEDICINE
AMINO ACIDS
ANIMALS
ANTIBODIES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
CARBOXYLIC ACIDS
CHELATING AGENTS
DAYS LIVING RADIOISOTOPES
DIAGNOSIS
DIAGNOSTIC USES
DISEASES
DRUGS
DTPA
ELECTRON CAPTURE RADIOISOTOPES
IMAGE PROCESSING
IMMUNOASSAY
IMMUNOLOGY
INDIUM 111
INDIUM 131
INDIUM ISOTOPES
INJECTION
INTAKE
INTERMEDIATE MASS NUCLEI
ISOMERIC TRANSITION ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LABELLING
MAMMALS
MICE
MINUTES LIVING RADIOISOTOPES
MONOCLONAL ANTIBODIES
NEOPLASMS
NUCLEI
ODD-EVEN NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
PROCESSING
PROTEINS
RADIOASSAY
RADIOIMMUNOASSAY
RADIOIMMUNOLOGY
RADIOISOTOPES
RADIOPROTECTIVE SUBSTANCES
REACTION KINETICS
RODENTS
SECONDS LIVING RADIOISOTOPES
TRACER TECHNIQUES
USES
VERTEBRATES