Opposing chemokine gradients control human thymocyte migration in situ
Joanna Halkias, … , Astar Winoto, Ellen A. Robey
Joanna Halkias, … , Astar Winoto, Ellen A. Robey
Published April 15, 2013
Citation Information: J Clin Invest. 2013;123(5):2131-2142. https://doi.org/10.1172/JCI67175.
View: Text | PDF
Research Article Immunology

Opposing chemokine gradients control human thymocyte migration in situ

Abstract

The ordered migration of thymocytes from the cortex to the medulla is critical for the appropriate selection of the mature T cell repertoire. Most studies of thymocyte migration rely on mouse models, but we know relatively little about how human thymocytes find their appropriate anatomical niches within the thymus. Moreover, the signals that retain CD4+CD8+ double-positive (DP) thymocytes in the cortex and prevent them from entering the medulla prior to positive selection have not been identified in mice or humans. Here, we examined the intrathymic migration of human thymocytes in both mouse and human thymic stroma and found that human thymocyte subsets localized appropriately to the cortex on mouse thymic stroma and that MHC-dependent interactions between human thymocytes and mouse stroma could maintain the activation and motility of DP cells. We also showed that CXCR4 was required to retain human DP thymocytes in the cortex, whereas CCR7 promoted migration of mature human thymocytes to the medulla. Thus, 2 opposing chemokine gradients control the migration of thymocytes from the cortex to the medulla. These findings point to significant interspecies conservation in thymocyte-stroma interactions and provide the first evidence that chemokines not only attract mature thymocytes to the medulla, but also play an active role in retaining DP thymocytes in the cortex prior to positive selection.

Authors

Joanna Halkias, Heather J. Melichar, Kayleigh T. Taylor, Jenny O. Ross, Bonnie Yen, Samantha B. Cooper, Astar Winoto, Ellen A. Robey

×

Figure 5

CCR7 signaling directs intrathymic localization of human CD8+ SP thymocytes.

Options: View larger image (or click on image) Download as PowerPoint
CCR7 signaling directs intrathymic localization of human CD8+ SP thymocy...
(A) Representative fixed cryosections of untreated and PTX-treated CD8+ SP human thymocytes overlaid on human thymic slices. (B) Relative density of PTX-treated CD8+ SP cells on human thymic slices. Data were compiled from at least 3 tissue sections from at least 2 independent experiments. n = 265 cells. Untreated CD8+ SP cells from Figure 1F are shown for comparison. (C) Cell tracks from representative 2-photon time-lapse datasets of untreated or PTX-treated CD8+ SP cells on CD11c-YFP thymic slices imaged in the medulla (20-minute movies). (D) Average speed of PTX-treated CD8+ SP cells in the medulla of CD11c-YFP thymic slices. Data were compiled from a minimum of 2 different imaging volumes from at least 2 experiments. n = 57 tracks. Untreated CD8+ SP cells from Figure 2B are shown for comparison. (E) Cell tracks from representative 2-photon time-lapse datasets of untreated or PTX-treated CD8+ SP cells on human thymic slices (30-minute movies). (F) Average speed of PTX-treated CD8+ SP cells on human thymic slices. n = 105 tracks. Untreated CD8+ SP cells from Figure 2D are shown for comparison. (G) Representative fixed cryosections of human thymocyte subsets overlaid on plt/plt thymic slices. (H) Relative density of each human thymic subset on plt/plt thymic slices. n = 2,210 cells (DP); 1,435 cells (CD4+); 8,271 cells (CD8+). Thymocyte subsets on WT slices from Figure 1D are shown for comparison. (A and G) Dashed outlines as in Figure 1. (B and H) Each dot represents quantification of 1 tissue section. (C–F) Track color-coding, symbols, and lines as in Figure 2. Scale bars: 100 μm (A and G); 30 μm (C and E). *P < 0.05.