TC-99M-CD19 MONOCLONAL-ANTIBODY IS NOT USEFUL FOR IMAGING OF B-CELL NON-HODGKINS-LYMPHOMA

In this study we investigated the applicability of Tc-99m-labeled CD19 monoclonal antibody (mAb) for tumor imaging in patients with B cell n on-Hodgkin's lymphoma. A 1-mg sample of murine CD19 mAb was labeled wi th approximately 550 MBq [Tc-99m]pertechnetate. The labeled mAb was ad ministered i.v. to seven patients, four without and three with pretrea tment with 10 mg unlabeled CD19 mAb. The number of circulating B cells was decreased by 44+/-5% 1 h after injection of the radiolabeled mAb. Peripheral B cells were coated with CD19, resulting in partial modula tion of CD19, most pronounced in the three pretreated patients. Whole- body images were obtained with a gamma camera and compared with result s obtained by conventional imaging techniques. Initially, blood-pool a ctivity dominated, whereas 24 h after injection the radioactivity was mainly located in the spleen, kidneys and liver. In two patients, a le sion in the spleen appeared as an unlabeled spot. In one patient, a le sion in the femur, which was detected by computed tomography (CT) and gallium-67 scans, was also seen on the CD19 scan from 1 h after admini stration of the radioimmunoconjugate onwards. Good imaging of bone mar row infiltration was observed in one of three patients. Lymph node inv olvement was not observed in any of the patients in whom affected lymp h nodes were detected by CT or gallium-67 scan. In conclusion, in the present study radioimmunodetection with 99(m)Tc-labeled CD19 mAb was f ound to be inferior to CT and gallium-67 scanning in the diagnosis of patients with B cell non-Hodgkin's lymphoma.