Recent Thymic Emigrants of the CD4 T-cell Lineage

描述（由申请方提供）：表达α-T细胞受体的抗原初始CD 4对于产生对新抗原的免疫应答至关重要，并且在胸腺内作为成熟的CD 4 + CD 8-胸腺细胞从头产生。这些细胞进入外周，成为初始CD 4 T细胞区室的近期胸腺移出物（RTE）。虽然监测CD 4 RTEs具有很大的临床意义，特别是在CD 4 T细胞淋巴细胞减少症中，但由于缺乏特异性表面标志物，对人CD 4 RTEs的直接评价受到限制。该项目将利用一种新的和最近发现的人类CD 4 RTE的表面标志物，蛋白酪氨酸激酶7（PTK 7），以确定CD 4 RTE的频率，表型和功能。初步结果验证了PTK 7作为CD 4 RTE标志物，并显示PTK 7 + CD 4 RTE与PTK 7初始CD 4 T细胞相比具有降低的效应子功能能力。目的1将通过未刺激和刺激的PTK 7 + CD 4 RTE和其他CD 4 T谱系细胞的深度mRNA测序，使用基因表达谱分析：1）确定个体发育期间PTK 7 + CD 4 RTE中残留胸腺细胞基因表达的程度，和2）鉴定参与降低的CD 4 RTE免疫功能的基因产物，特别是对于Th 1产生和/或将PTK 7 + CD 4 RTE细分为更多与更少最近的胸腺移出者。目的2将使用体内标记来检验PTK 7 + CD 4 RTEs是PTK 7- naive CD 4 T细胞的直接前体的假设，并将确定PTK 7 + CD 4 RTEs在维持HIV-1感染中的naive CD 4 T细胞数量和12-TCR库多样性中的作用。目的3将使用类似的方法来测试PTK 7 + CD 4 RTEs在异基因造血干细胞移植后初始CD 4 T细胞的免疫重建中的重要性。目的4将确定胸腺完全切除术后儿童和成人PTK 7 + CD 4 RTE丢失的动力学，以及这种丢失对初始CD 4 T细胞数量和12- TCR库多样性的影响。总之，这些研究将大大提高我们对胸腺RTE产生在维持健康和疾病中外周幼稚CD 4 T细胞区室中的作用的理解。

DESCRIPTION (provided by applicant): Antigenically naive CD4 expressing a¿-T cell receptors are critical for generating immune responses to neoantigens, and are produced de novo within the thymus as mature CD4+CD8- thymocytes. These enter the periphery to become recent thymic emigrants (RTEs) of the naive CD4 T-cell compartment. Although monitoring of CD4 RTEs is of great clinical interest, particularly in CD4 T-cell lymphopenia, direct evaluation of human CD4 RTEs has been limited by a lack of specific surface markers. This project will utilize a novel and recently identified surface marker for human CD4 RTEs, protein tyrosine kinase 7 (PTK7), to define CD4 RTE frequency, phenotype, and function. Preliminary results validate PTK7 as a CD4 RTE marker, and show that PTK7+ CD4 RTEs have a reduced capacity for effector function compared to PTK7- naive CD4 T cells. Aim 1 will use gene expression profiling by deep mRNA sequencing of unstimulated and stimulated PTK7+ CD4 RTEs and other CD4 T-lineage cells to: 1) define the extent of residual thymocyte gene expression in PTK7+ CD4 RTEs during ontogeny, and 2) identify gene products involved in reduced CD4 RTE immune function, particularly for Th1 generation and/or that subdivide PTK7+ CD4 RTEs into more versus less recent thymic emigrants. Aim 2 will use in vivo labeling to test the hypothesis that PTK7+ CD4 RTEs are the direct precursors of PTK7- naive CD4 T cells, and will determine the role of PTK7+ CD4 RTEs in maintaining naive CD4 T-cell numbers and 12-TCR repertoire diversity in HIV-1 infection. Aim 3 will use a similar approach to test the importance of PTK7+ CD4 RTEs in immune reconstitution of naive CD4 T cells after allogeneic hematopoietic stem cell transplantation. Aim 4 will define the kinetics of loss of PTK7+ CD4 RTEs in children and adults following complete thymectomy and the impact of this loss on naive CD4 T-cell numbers and 12- TCR repertoire diversity. Together, these studies will substantially enhance our understanding of the role of thymic RTE production in maintaining the peripheral naive CD4 T-cell compartment in health and disease.