RESUMO
Objective To study the effect of two-step pretargeting radioimmunotherapy of CD45 McAb and 188Re-Avidin on lymphoma Raji cell line.Methods The CD45 McAb and Avidin were directly labeled with 188Re,and the labeling efficiency and radiochemical purity were measured by the paper chromatography.The specific binding test and competition binding test between 188 Re-CD45 McAb and Raji cells in vitro were also performed.CCK-8 assay was used to determine the inhibition effect on Raji cell proliferation in the pretargeted group,188Re-CD45 McAb,188Re-Avidin and 188ReO4 groups,then the cell survival and proliferation inhibition rate were calculated.Results The specific cell binding rate of 188Re-CD45 McAb with Raji cells was (70.92 ± 1.91) ％,in the competition group,the binging rate of 188Re-CD45 McAb with Raji cells was only (7.96 ± 0.87)％.The Raji cells proliferation was inhibited in all groups with 188Re radiolabel,and the inhibition rate was positively correlated with the radioactivity dose (r=0.907-0.992,P ＜0.05).However,at the same dose,the inhibition effect in the group of two-step pretargeting at each time point were all stronger than those of 188Re-CD45 McAb,188Re-Avidin and 188 ReO4-alone (t =124.76-607.98,P ＜ 0.05).But there was no significantly statistical difference in the inhibitory effect between the groups of 188Re-Avidin and 188ReO4-(P ＞ 0.05).Conclusions It is confirmed that 188Re-CD45 McAb could be specifically bound to Raji cells,and the two-step pretargeting of CD45 McAb and 188Re-Avidin has obvious inhibitory effect on the Raji cell proliferation.