en Radiation Biology Radiation Biology تحقيق بديع Original Research <span style="font-weight: bold"> Background:</span> In order to obtain an anti-CD20 conjugate to be used in future therapeutic studies with therapeutic radioisotopes, 67Ga-labeled antibody was prepared as a model of metal chelated immunoconjugate for preliminary dosimetric and biodistribution studies. <span style="font-weight: bold">Materials and Methods:</span> Rituximab was labeled with [67Ga]-gallium chloride after residulation with freshly prepared cyclic DTPAdianhydride. The best results of the conjugation were obtained by the addition of 1 ml of a rituximab pharmaceutical solution (5 mg/ml, in phosphate buffer, pH=8) to a glass tube pre-coated with DTPAdianhydride (0.01 mg) at 25|o|C with continuous mild stirring for 30 min. The final isotonic 67Ga-DTPArituximab complex was checked by gel electrophoresis for radiolysis/chemolysis control. Radio-TLC was performed to ensure the formation of only one species. Preliminary in vivo studies in normal rat model were performed to determine the biodistribution of the radioimmunoconjugate up to 6 hours. <span style="font-weight: bold">Results:</span> Radio-thin layer chromatography showed an overall radiochemical purity of 96-99% at optimized conditions (specific activity =300-500 MBq/mg, labeling efficiency 77%). Gel electrophoresis showed no protein cleavage after radiolabeling. <span style="font-weight: bold">Conclusion:</span> Preliminary in vivo studies in normal rat model showed [67Ga]-DTPA-rituximab is a good probe for bio-dosimetry of therapeutic rituximab conjugates. <br>Iran. J. Radiat. Res., 2007 4 (4): 187-193 Gallium-67, rituximab, radiolabeling, biodistribution, cyclotron. 187 196 http://ijrr.com/browse.php?a_code=A-10-1-222&slc_lang=en&sid=1 A. R. Jalilian ajalilian@nrcam.org 79003194753284600676 79003194753284600676 Yes L. Mirsadegh 79003194753284600677 79003194753284600677 No R. Haji-Hosseini 79003194753284600678 79003194753284600678 No S. Rajabifar 79003194753284600679 79003194753284600679 No F. Bolurinovin 79003194753284600680 79003194753284600680 No