RESUMO
<p><b>OBJECTIVE</b>To study the biological response of B-cell lymphoma cells positive for CD20 expression to (131)I-labeled rituximab.</p><p><b>METHODS</b>Anti-CD20 monoclonal antibody rituximab was labeled with (131)I by means of IODO-GEN method, and its effects on apoptosis of Raji cells were determined by Annexin-V/PI double-labeled cytometry. Its effects on the cell cycles was evaluated by cytometry with PI staining.</p><p><b>RESULTS</b>The cell apoptosis rate measured by Annexin v-FITC/PI was 51.99% in (131)I-rituximab group, significantly higher than that in (131)I group, rituximab group and control group (42.71%, 29.42% and 26.17%, respectively, P<;0.05). The apoptosis rate by flow cytometry with PI staining was 4.32% in (131)I-rituximab group, also significantly higher than that in the other 3 groups (1.47%, 1.39% and 0.37%, respectively, P<0.05). Cell cycle alteration of Raji cells occurred in (131)I-rituximab group, and the majority of cells were arrested at G(1)/G(2) stage.</p><p><b>CONCLUSION</b>(131)I-rituximab can regulate the cell cycle of Raji cells and induce their apoptosis to inhibit their proliferation.</p>