Objective To explore the antigen presentation of CT26.WT via intra-peritoneal injection. Methods The intra-peritoneal injection model was made via injecting cell suspensions in mice. The spleen was isolated from BALB/c mice toco-culture with CT26.WT to detect tumor-killed ability. Phenotype identification methods and CCK8 massy were used to measure the ability of antigen presentation and stimulate T lymphocyte proliferation. IHC was used to detect the expression of B7H4 in normal and tumor tissues. Results Along with the extension of intra-peritoneal injection, the surviving number of cells was increased, contrary to the apoptosis. DC cells failed in maturation and impaired in stimulating T lymphocyte proliferation. B7H4 was higher in tumor tissues. Conclusions With the extension of intra-peritoneal injection, the mature DC cells were scared in number, resulting in the impairement of antigen-presentation. Moreover, the higher B7H4 expression in tumor tissues led to the lack of second signals which may stimulate T cells. Consequently, the ability of T cells in killing tumor cells was decreased so that they escape immunosurveillance.%目的：构建腹腔注射小鼠结直肠癌细胞系 CT26．WT模型来检测树突状细胞（DC）抗原递呈的细胞免疫抑制。方法：CT26．WT细胞腹腔注射入BALB／c小鼠体内，脾脏分离T细胞，与CT26．WT细胞共培养；流式表型鉴定DC细胞的免疫学标记，再与T细胞共培养，观察DC细胞抗原递呈能力及体外刺激T细胞的增殖能力。 IHC检测正常结肠上皮与结直肠癌组织B7H4的表达。结果：随着腹腔注射时间的延长，共培养体系中活细胞增加，凋亡率降低，DC细胞不能发育成熟，T细胞增殖能力下降。配对的癌组织B7H4表达增高。结论：随着腹腔注射时间的延长，DC细胞的成熟发生障碍，抗原递呈能力下降。另外，结直肠癌高表达负性共刺激分子B7H4，T细胞活化受到抑制，T细胞杀伤肿瘤细胞的能力下降，肿瘤细胞发生免疫逃逸。
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