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マウス腹腔NKT細胞の抗腫瘍活性：川村俊彦¹,竹田和由²,安保徹¹（¹新潟大・医・医動物,²順天堂大・医・免疫）

Protective effect of NK1.1⁺αβ T cells as well as NK cells against intraperitoneal tumors in mice: Toshihiko KAWAMURA¹, Kazuyoshi TAKEDA², Toru ABO¹ (¹Dept. of Immunol. Niigata Univ. Sch. Med., ²Dept of Immunol. Juntendo Univ. Sch. Med.)

Peritoneal resident cells of mice normally contain small populations of NK cells and NK1.1⁺αβ T cells. These populations increased after either 3LL or EL4 tumor inoculations into the peritoneal cavity. In vivo depletion of NK cells alone by anti-asialo GM1(ASGM1) Ab significantly decreased survival time of tumor injected mice, while depletion of both NK cells and NK1.1⁺ T cells by anti-NK1.1 Ab greatly shortened mouse survival time. NK1.1⁺ T cells in peritoneal cavity consist of a larger proportion of double negative T cells, smaller populations of CD4+ T cells and Vb8⁺ T cells as compared with liver NK1.1⁺ T cells, and normally lack Vβ2⁺ T cells. Tumor inoculation induced rapid IL-12 and IFN-γ mRNA in tumor infiltrating mononuclear cells (TIM). Although anti-NK1 Ab pretreatment in vivo abrogated IFN-γ mRNA expression and IFN-γ production of TIM, NK cell depletion alone by anti-ASGM1 Ab pretreatment retained IFN-γ mRNA expression and partly inhibited IFN-γ production of TIM. Further, peritoneal NK cells as well as NK1.1⁺ T cells but not NK1.1^- T cells of 3LL cell injected mice showed cytotoxicities against the same tumor cells. Our findings suggest that peritoneal macrophages activated by tumors produce IL-12, which activates NK cells and NK1.1⁺ T cells to produce IFN-γ. Further, both NK cells and NK1.1⁺ T cells are important in suppressing the growth of intraperitoneal tumors.