[In vitro cytotoxicity of 131I-Rituximab against B-cell lymphoma cells].
OBJECTIVE
To study the specific cytotoxicity of (131)I-Rituximab against CD20-positive B-cell lymphoma cells.


METHODS
Rituximab was labeled with (131)I using IODO-GEN method, and the dose-effects of various concentrations of (131)I-Rituximab, (131)I alone and Rituximab in Raji cells were evaluated by MTT assay to determine the optimal dose according to the dose-effect curves. The cytotoxicity of (131)I-Rituximab, (131)I and Rituximab was assessed in CD20-positive Ramos (RA-1) cells, Raji cells and CD20-negative Molt-4 cells according to the changes of the survival rates. Giemsa staining was used to evaluate the antitumor effect of (131)I-Rituximab in Raji cells by measuring the mitosis index (MI).


RESULTS
(131)I-Rituximab presented with a dose-dependent cytotoxicity against Raji cells. At the specific activity of 60 microCi/ml, (131)I-Rituximab resulted in significantly higher growth inhibition rate of the cells than Rituximab (P<0.05). The inhibition rate of Raji cells treated with (131)I-Rituximab, (131)I, or Rituximab for 96 h were comparable with the rates in Ramos RA-1 cells, but significantly higher than the rates in Molt-4 cells. The MI values in (131)I-Rituximab group were significantly lower than those in the other groups (P<0.001).


CONCLUSIONS
(131)I-Rituximab can induce specific cytotoxicity against CD20-positive tumor cells, and may potentially serve as an agent for targeted radioimmunotherapy for CD20-positive B-cell lymphoma.
Wei
Li
L
Center of Oncology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China.
Luo
Rong-cheng
RC
Zhang
Jun-yi
JY
Yan
Xiao
X
Lü
Cheng-wei
CW
D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D058846:Antibodies, Monoclonal, Murine-Derived; D018951:Antigens, CD20 / Q000276:immunology; D017209:Apoptosis / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007457:Iodine Radioisotopes / Q000494:pharmacology; D016393:Lymphoma, B-Cell / Q000473:pathology*; D016499:Radioimmunotherapy; D000069283:Rituximab; D014407:Tumor Cells, Cultured
D000911:Antibodies, Monoclonal; D058846:Antibodies, Monoclonal, Murine-Derived; D018951:Antigens, CD20; D007457:Iodine Radioisotopes; D000069283:Rituximab; C507388:131I-rituximab