The effect of radiation therapy on Primary Effusion Lymphoma

Abstract

[abstract] The number of HIV-1 infected patients is growing in Japan every year. Prognosis of the HIV-1 infected patients is improved dramatically by progress of drug treatment, but recently malignant tumors, in particular, malignant lymphoma becomes major problem for long-term prognosis. Primary Effusion Lymphoma (PEL) is a nonspecific disease relatively seen in the HIV infected patients and is well known that its stronger chemotherapy resistance makes the prognosis extremely poor. In this study, we examined the effectiveness of the radiotherapy for PEL using the culture cells and the Balb/c Rag-2/Jak3 double deficient mice models. [method] 1. We investigated radiosensitivity of the PEL cell strain (BCBL-1, BC-1, BC-3, TY-1). Using ¹³⁷Cs gamma rays (662 keV), the change of the cell counts after the radiation exposure by means of MTT method and a cell count measurement with Trypan Blue was analyzed and compared with other blood malignant tumors stock (Raji, Jurkat, K562). In addition, we confirmed whether or not these cells were induced apoptosis with DNA, ladder, and Annexin V dyeing. 2. We made a model mouse of PEL by transplanting PEL cell strain under the skin or in the abdominal cavity of severe immnodeficient mice (Balb/c Rag-2/Jak3 double deficient mice). After radiation exposure to these mice (whole body, 4 Gy*2), bone marrow transplantation was performed. [result] 1. The radiosensitivity of the PEL cell strain was significantly high in comparison with other blood malignant tumors stock. It was confirmed that PEL cell strains were induced to apoptosis with DNA, ladder, and Annexin V dyeing. 2. On the model of subcutaneous inoculation of BCBL-1, the non-irradiation group showed temporal tumor growth under the skin and all died 6 weeks after tumor implantation. However, in the irradiation group, such a tumor growth was not recognized 6 weeks after tumor implantation. In the model for the intraperitoneal injection of BC-3, the non-treatment group developed ascites, but in the irradiated treatment group the development of ascites was not recognized 6 weeks after tumor implantation. [conclusions] It was found that radiosensitivity of the PEL cell strain is significantly high. It was suggested that radiotherapy is very useful to PEL which has malignancy and resistance to chemotherapy.