Quantification of dendritic cell subsets in human thymus tissues of various ages

Yan Li,Huiyu Feng,Hao Huang,Hao Ran,Weibin Liu,Pei Chen

doi:10.1186/s12979-021-00255-8

Abstract

BackgroundDendritic cells (DCs) in the thymus are involved in central tolerance formation, but they also have other functions in the thymus, such as pathogen recognition. The density changes of human thymic DCs have been hardly investigated. In this study, human thymus samples of various ages were collected for tissue sectioning and staining. The thymic cortex and medulla area as well as the densities of various subsets of thymic DCs were calculated.ResultsAll common DC subsets were found in the human thymus of various ages. Most DCs had accumulated in the human thymic epithelial space, especially the medulla. We also found that the human thymic cortex had atrophied relatively faster than the medulla, which led to a gradual increase of the area ratio of the medulla to cortex with the increase of age. The densities of DC subsets in the human thymus showed various changes with increasing age, which contributed to the composition changes of DC subsets. The density of plasmacytoid DCs (pDCs) in the human thymus had increased gradually with aging, which suggested that pDCs plays another essential role in the thymus in addition to central tolerance.ConclusionsInconsistent with the shrinking of the epithelial space in the thymus, the densities of DC subsets in the epithelial space of the thymus are maintained at a constant level with aging to preserve highly efficient autoreactive thymocyte screening. An increasing density of the thymic pDCs with aging implies an extra function of DCs in the thymus beyond central tolerance.

Highlights

Dendritic cells (DCs) in the thymus are involved in central tolerance formation, but they have other functions in the thymus, such as pathogen recognition
Dendritic cell subsets and morphological characteristics in the human thymus Thymus tissue was digested into a single cell suspension and dendritic cells in the thymus were analyzed by flow cytometry
Using CD123 and CD11c as markers in immunohistochemistry, the two subsets of DCs were identified in thymus tissue (Fig. 1C). plasmacytoid DCs (pDCs) were elliptic and granular, while myeloid dendritic cells (mDCs) were typical dendrite-like with irregular shapes and many projections

Summary

Introduction

Dendritic cells (DCs) in the thymus are involved in central tolerance formation, but they have other functions in the thymus, such as pathogen recognition. The thymus is the central lymphoid organ in which T cells develop and mature During this process, the body executes a series of elaborate mechanisms to remove thymocytes that cannot recognize their own human leukocyte antigen (HLA) or autoreactive thymocytes and outputs naive T cells and natural regulatory T cells. The body executes a series of elaborate mechanisms to remove thymocytes that cannot recognize their own human leukocyte antigen (HLA) or autoreactive thymocytes and outputs naive T cells and natural regulatory T cells This is the formation of central tolerance, which is a critical component of immune. Regardless of the origin, DCs in the thymus participate in central tolerance formation and are mainly concentrated in the medulla. DCs in the medulla collect various common self-antigens and tissue-restricted antigens expressed by thymic epithelial cells.

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