ABSTRACT
PURPOSE: Radiolabeled CEA79.4 antibody has a possibility to be used in radioimmunoscintigraphy or radioimmunotheraphy of cancer. We investigated the in vitro properties and biodistribution of CEA79.4 antibody labeled with Re-188 or Tc-99m. MATERIALS AND METHODS: CEA79.4 was reduced by 2-mercaptoethanol to produce-SH reside, and was labeled with Re-188 or Tc-99m. For direct labeling of Tc-99m, methylene-diphosphonate was used as transchelating agent. CEA79.4 in 50 mM Acetate Buffered Saline (ABS, pH 5.3) was labeled with Re-188, using stannous tartrate as reducing agent. In order to measure immunoreactivity and the affinity constant of radiolabeled antibody, cell binding assay and Scatchard analysis using human colon cancer cells SNU-C4, were performed. Biodistribution study of labeled CEA79.4 was carried out at 1, 14 and 24 hr in ICR mice. RESULTS:. Labeling efficiencies of Tc-99m and Re-188 labeled antibodies were 92.4+/-5.9% and 84.7+/-4.6%, respectively. In vitro stability of Tc-99m-CEA79.4 in human serum was higher than Re-188-CEA79.4. Immunoreactivity and affinity constant of Tc-99m-CEA79.4 were 59.2% and 6.59x109 M-1, respectively, while those of Re-188-CEA79.4 were 41.6% and 4.2x109 M-1, respectively. After 24 hr of administrations of Re-188 and Tc-99m labeled antibody, the remaining antibody, the remaining antibodies in blood were 6.32 and 9.35% ID/g respectively. The biodistribution of each labeled antibody in other organs was similar because they did not accumulate in non-targeted organs. CONCLUSION: In vitro properties and biodistribution of Re-188-CEA79.4 were similar to those of Tc-99m-CEA79.4. It appears that Re-188-CEA79.4 can be used as a suitable agent for radioimmunotherapy.
Subject(s)
Animals , Humans , Mice , Antibodies , Colonic Neoplasms , Hydrogen-Ion Concentration , Mercaptoethanol , Mice, Inbred ICR , Radioimmunodetection , RadioimmunotherapyABSTRACT
PURPOSE: The purpose of this study was to evaluate the diagnostic accuracy of Tc-99m labeled antigranulocyte antibody immunoscintigrapy in the diagnosis of osteomyelitis and compare with the results of triphasic bone scan. MATERIALS AND METHODS: The study population was 39 patients (22 male, 17 female) who had uncertain diagnoses of osteomyelitis. Fifteen patients had history of orthopedic surgery, and 5 had previous fracture. One milligram of monoclonal antibody against NCA-95 was labeled with 370 MBq of Tc-99m, injected intravenously, and 4 hour images were obtained. Triphasic bone scan images were obtained in 30 p;tients. The final diagnosis was confirmed by bacteriologic culture, biopsy or long term clinical follow up. RESULTS: Twenty one patients were confirmed to have osteomyelitis (1 acute, 20 chronic). Eighteen patients were without osteomyelitis. Antigranulocyte antibody immunoscintigraphy had a sensitivity of 71% (15/21), and a specificity of 89% (16/18), while the sensitivity and specificity of triphasic bone scan was 93% (13/14) and 38% (6/16), respectively. Antigranulocyte antibody scan showed higher specificity of 100% (11/11) in comparison with 33% (3/9) of triphasic bone scan in patients with history of orthopedic surgery or fracture. CONCLUSION: Antigranulocyte antibody immunoscintigraphy is more specific than that of triphasic bone scan and may be helpful in patients with history of surgery or fracture. However, sensitivity is lower than triphasic bone scan in the detection of chronic osteomyelitis.