直肠癌患者接受术前新辅助放化疗可以有效的降低肿瘤分期、提高保肛率、降低局部复发率。但目前尚不清楚新辅助治疗是否以及如何影响组织的抗肿瘤免疫应答。我们新近发现：在直肠癌引流淋巴结中存在一群CD169+CD8+T细胞亚群，该亚群在对新辅助治疗有效组患者淋巴结中的比例明显高于治疗无效组。提示，CD169+T细胞可能参与了抗肿瘤免疫应答，与新辅助治疗效果密切相关。以此为基础，本课题拟结合临床样本分析和实验模型来：1）明确直肠癌淋巴结中浸润的CD169+T细胞的功能与表型；2）研究肿瘤微环境调控T细胞表达CD169的具体机制；3）探讨新辅助治疗中的多类不同化疗药物对CD169+T细胞数量和功能的影响；4）利用大规模临床样本探讨该细胞亚群对新辅助效果的预测能力。所得结果将帮助我们理解新辅助治疗对机体免疫系统影响的具体机制，为筛选合适的患者进行新辅助治疗后的强化治疗提供理论依据。

Colorectal cancer patients received preoperative neoadjuvant chemoradiation can achieve tumor down staging, better sphincter reserve rate, and lower local recurrence rate. It is still unclear whether neoadjuvant therapy can trigger antitumor immune response in those patients. Our recent study demonstrated that there is a group of CD169 + CD8 + T cells in regional lymph nodes of rectal cancer, especially in the lymph nodes of patients who respond better to neoadjuvant therapy than those who did not. We hypothesize that CD169 + T cells may participate in antitumor immune response, which could influence the effect of neoadjuvant therapy. To gain a better understanding of this assumption, we plan to use clinical sample analysis and experimental stuydies to: 1) characterize the phenotype and function activities of CD169 + T cells in rectal cancer ; 2) dissect the underlying mechanism that regulate the generation and function of CD169+ T cells of tumor microenvironment; 3) investigate the impact of different types of chemotherapy drugs on CD169 + T cell; 4) validate the above hypothesis in large clinical samples. The results obtained from this project will help us to better understand the mechanism of immune system, and to select the appropriate patient after neoadjuvant therapy for the following intensive treatment.