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Updated: Jun 25, 2026

Characterization of Thymic Settling Progenitors in the Mouse Embryo Using In Vivo and In Vitro Assays
08:56

Characterization of Thymic Settling Progenitors in the Mouse Embryo Using In Vivo and In Vitro Assays

Published on: June 9, 2015

Thymus-homing peripheral dendritic cells constitute two of the three major subsets of dendritic cells in the

JiChu Li1, JooHung Park, Deborah Foss

  • 1Department of Viral Pathogenesis, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA.

The Journal of Experimental Medicine
|March 11, 2009
PubMed

Many dendritic cells (DCs) in the normal mouse thymus are generated intrathymically from common T cell/DC progenitors. However, our previous work suggested that at least 50% of thymic DCs originate independently of these progenitors. We now formally demonstrate by parabiotic, adoptive transfer, and developmental studies that two of the three major subsets of thymic DCs originate extrathymically and continually migrate to the thymus, where they occupy a finite number of microenvironmental niches. The thymus-homing DCs consisted of immature plasmacytoid DCs (pDCs) and the signal regulatory protein alpha-positive (Sirpalpha(+)) CD11b(+) CD8alpha(-) subset of conventional DCs (cDCs), both of which could take up and transport circulating antigen to the thymus. The cDCs of intrathymic origin were mostly Sirpalpha(-) CD11b(-) CD8alpha(hi) cells. Upon arrival in the thymus, the migrant pDCs enlarged and up-regulated CD11c, major histocompatibility complex II (MHC II), and CD8alpha, but maintained their plasmacytoid morphology. In contrast, the migrant cDCs proliferated extensively, up-regulated CD11c, MHC II, and CD86, and expressed dendritic processes. The possible functional implications of these findings are discussed.

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