Distribution And Clinical Significance Of Plasmacytoid Dendritic Cells In Colorectal Cancer

Dendritic cells(DCs) are professional antigen presenting cells(APCs)with the capacity to prime and activate na?ve T lymphocytes.DCs can be divided morphologically and functionally into two types: conventional DCs(cDCs)and plasmacytoid DCs(pDCs).pDCs also known as interferon-producing cells,can regulate the ability of NK cells,T cells,B cells and cDCs by mass production of type I interferons,linking innate immunity and adaptive immunity.pDCs represent 0.2%–0.8% of peripheral blood mononuclear cells in both humans and mice.In the development of the tumor,its number and positioning will change.Studies have shown that,in tumor tissues,pDCs mainly distributed in the T cell area of lymph nodes.Tertiary lymphoid structures(TLSs)are ectopic lymphatic structures that occur during inflammation,infection,or tumorigenesis.They do not belong to the classical secondary lymphoid organs,but have a structure of classical secondary lymphoid organs such as B cells,T Cells,DC.Classical TLSs can also be found the germinal center and other structures.A number of studies have shown that the emergence of TLSs and tumor prognosis.The aim of this study was to investigate the changes of pDCs in the number and distribution of different tissues of colorectal cancer,and to explore the possibility of pDCs as a vaccine for clinical immunotherapy.In the experiment,66 patients with newly diagnosed colorectal cancer treated in 309 Hospital of PLA from February 2016 to December 2016 were selected.We took peripheral blood sample from patients,analyzed the number of pDCs by flow cytometry in peripheral blood mononuclear cells.Collected the tumor tissues and paratumor tissues,then analyzed by flow cytometry and immunohistochemical staining.Analyzed the relationship between experimental results and general clinical data.Flow cytometry analysis showed that the proportion of pDCs in the peripheral blood of patients was reduced.Compared with paratumor tissues,flow cytometry and immunohistochemical staining showed that the number of pDCs in tumor tissues increased,the difference was statistically significant(P <0.05).Immunohistochemical staining also showed that pDCs was mainly distributed in the T cell zone of the TLSs in the mucosal layer of colorectal cancer tissues.Analyze the correlation between pDCs and clinical data,the results showed that p DC was significantly associated with clinical stage and lymph node metastasis of colorectal cancer(P <0.05).The positive rate of TLS was related to the degree of lymph node metastasis,the difference was statistically significant(P <0.05).The results showed that the number of pDCs changed significantly in different tissues of colorectal cancer patients,and was related with the clinical stage and lymph node metastasis.Immunotherapy for pDCs in tumor tissues may be a new treatment for colorectal cancer.In addition,pDCs is mainly distributed in the TLSs of tumor tissues,suggesting that pDCs and TLSs may work together on the process of tumor.Changing the environment of the TLSs may also alter the function of pDCs in tumor tissues and provide new ideas for immunotherapy of colorectal cancer.