People with low immunity are susceptible to cancer:the occurrence,development,recurrence rate and survival period of tumors are closely related to the immune status of the body.The human immune system is composed of immune organs,immune cells,immune molecules,and lymphatic circulation network.Immune cells circulate through the blood to various organs and tissues throughout the body.

 Through the quantitative analysis of the changes in the proportion of T lymphocyte subsets in human peripheral blood,the qualitative and quantitative analysis of the diversity of T cell antigen receptors(T CELL RECEPTOR,TCR)to determine the cellular immune response capacity of human individuals(including anti-tumor Ability and anti-infection ability)to guide the determination of clinical anti-tumor treatment plan.

 1.What is T cell receptor

 "The receptor that specifically recognizes the antigen on the surface of mature T cells is called the T cell antigen receptor(TCR),which is also a characteristic surface marker of all T cells."95%of TCRs are heterodimers composed ofαandβchains.Human TCRβchain genes are more complicated,and gene rearrangements occur in the process of antigen recognition,which play an important role.

 TCRβgene complex includes at least 67 V(variable)gene regions,2 D(diversity)gene regions,13 J(joining)gene regions and 2 C(constant)gene regions.

 2,the significance of detecting the CDR3 of TCR

 "In the process of T cell recognition of vaccines or tumor antigens,the complementarity determining region 3(CDR3,composed of three regions V,D,and J)on the Vβgene plays an important role.Specific as shown in Figure 1:

 If a clonal change in the CDR3 region of a TCR Vβfamily is detected,it indicates that T cells have specifically responded to a certain antigen.

 Under normal circumstances,with the increase of age,due to the increase in the number of exposure to pathogens,the maintenance of lymphocyte function and the decrease in the number of innocent T cells,the diversity distribution of TCR decreases.In general,young individuals have more polymorphisms in TCR.The distribution is normal,but the proportion of clonal distribution among elderly individuals increases.

 　   TCR的多态性表示T细胞种类或亚群的丰富多彩。

 　   一般来说，CD8+TCR的多态性与年龄相关，随着年龄增加而下降;而CD4+TCR的多态性与年龄的变化无明显关系。在相同年龄下，TCR多态性表达下降表示T细胞亚群减少或消失，对某种新抗原的应答能力下降。

 　    所以，准确、特异地定量化检测CDR3区T细胞多态性和克隆化程度可直接反映出T细胞的功能及免疫应答状态，在细胞免疫治疗中能够做到预测疗效、个性化调整治疗方案及准确地判断预后。还可用于抗病毒治疗或骨髓移植后的免疫重建，以及自身免疫性疾病的检测，包括I型糖尿病治疗的生物标志物等。