Key Points
-
The seeding of the thymus is mediated by at least two different pathways: the vasculature-independent embryonic pathway, in which the role of chemokines, such as CC-chemokine ligand 21 (CCL21) and CCL25, has been implicated, and the vasculature-dependent postnatal pathway, in which the adhesive interaction between platelet (P)-selectin and P-selectin glycoprotein ligand 1 is involved.
-
In the postnatal thymus, double-negative (DN) thymocytes relocate outwards from the cortico–medullary junction to the subcapsular region of the thymic cortex. The role of several chemokine receptors, including CXC-chemokine receptor 4 (CXCR4), CC-chemokine receptor 7 (CCR7) and CCR9, has been described.
-
Positively selected DP thymocytes relocate from the cortex to the medulla. Chemotaxis through CCR7 expressed by T-cell-receptor-stimulated thymocytes and CCR7 ligands expressed by medullary thymic epithelial cells is involved in this cortex-to-medulla migration.
-
The medulla is implicated in the establishment of tolerance to tissue-specific antigens and the generation of regulatory T cells.
-
Chemotaxis through sphingosine-1-phosphate (S1P) receptor 1 expressed by mature single-positive thymocytes and circulating S1P seems to be involved in thymocyte export from the adult thymus.
-
The generation of multiple microenvironments in the thymus, such as the cortex and the medulla, requires crosstalk signals from developing thymocytes.
Abstract
Lympho–stromal interactions in multiple microenvironments within the thymus have a crucial role in the regulation of T-cell development and selection. Recent studies have implicated that chemokines that are produced by thymic stromal cells have a pivotal role in positioning developing T cells within the thymus. In this Review, I discuss the importance of stroma-derived chemokines in guiding the traffic of developing thymocytes, with an emphasis on the processes of cortex-to-medulla migration and T-cell-repertoire selection, including central tolerance.
This is a preview of subscription content, access via your institution
Relevant articles
Open Access articles citing this article.
-
T cells in health and disease
Signal Transduction and Targeted Therapy Open Access 19 June 2023
-
How autoreactive thymocytes differentiate into regulatory versus effector CD4+ T cells after avoiding clonal deletion
Nature Immunology Open Access 23 March 2023
-
Mesenchymal stromal cells in the thymus
Inflammation and Regeneration Open Access 02 November 2022
Access options
Subscribe to this journal
Receive 12 print issues and online access
$209.00 per year
only $17.42 per issue
Rent or buy this article
Prices vary by article type
from$1.95
to$39.95
Prices may be subject to local taxes which are calculated during checkout




References
Miller, J. F. A. P. Immunological function of the thymus. Lancet 2, 748–749 (1961).
Bevan, M. J. In a radiation chimaera, host H-2 antigens determine the immune responsiveness of donor cytotoxic cells. Nature 269, 417–418 (1977).
Zinkernagel, R. M. et al. On the thymus in the differentiation of “H-2 self-recognition” by T cells: evidence for dual recognition? J. Exp. Med. 147, 882–896 (1978).
Sainte-Marie, G. & Leblond, C. P. Cytologic features and cellular migration in the cortex and medulla of thymus in the young adult rat. Blood 23, 275–299 (1964).
Cantor, H. & Weissman, I. Development and function of subpopulations of thymocytes and T lymphocytes. Prog. Allergy 20, 1–64 (1976).
Stutman, O. Intrathymic and extrathymic T cell maturation. Immunol. Rev. 42, 138–184 (1978).
Bhan, A. K., Reinherz, E. L., Poppema, S., McCluskey, R. T. & Schlossman, S. F. Location of T cell and major histocompatibility complex antigens in the human thymus. J. Exp. Med. 152, 771–782 (1980).
Petrie, H. T. Cell migration and the control of post-natal T-cell lymphopoiesis in the thymus. Nature Rev. Immunol. 3, 859–866 (2003).
Gray, D. H. D. et al. Controlling the thymic microenvironment. Curr. Opin. Immunol. 17, 137–143 (2005).
Scollay, R. G., Butcher, E. C. & Weissman, I. L. Thymus cell migration. Quantitative aspects of cellular traffic from the thymus to the periphery in mice. Eur. J. Immunol. 10, 210–218 (1980).
Egerton, M., Scollay, R. & Shortman, K. Kinetics of mature T-cell development in the thymus. Proc. Natl Acad. Sci. USA 87, 2579–2582 (1990).
Goldrath, A. W. & Bevan, M. J. Selecting and maintaining a diverse T-cell repertoire. Nature 402, 255–262 (1999).
Shores, E. W., van Ewijk, W. & Singer, A. Disorganization and restoration of thymic medullary epithelial cells in T cell receptor-negative scid mice: evidence that receptor-bearing lymphocytes influence maturation of the thymic microenvironment. Eur. J. Immunol. 21, 1657–1661 (1991).
van Ewijk, W., Shores, E. W. & Singer, A. Crosstalk in the mouse thymus. Immunol. Today 15, 214–217 (1994). References 13 and 14 were the first to show that thymocyte development affects the development of TECs, coining the idea of crosstalk in the thymus.
Hollander, G. A. et al. Developmental control point in induction of thymic cortex regulated by a subpopulation of prothymocytes. Nature 373, 350–353 (1995).
van Ewijk, W., Hollander, G., Terhorst, C. & Wang, B. Stepwise development of thymic microenvironments in vivo is regulated by thymocyte subsets. Development 127, 1583–1591 (2000).
Owen, J. J. & Ritter, M. A. Tissue interaction in the development of thymus lymphocytes. J. Exp. Med. 129, 431–442 (1969).
Haynes, B. F. & Heinly, C. S. Early human T cell development: analysis of the human thymus at the time of initial entry of hematopoietic stem cells into the fetal thymic microenvironment. J. Exp. Med. 181, 1445–1458 (1995).
Bleul, C. C. & Boehm, T. Chemokines define distinct microenvironments in the developing thymus. Eur. J. Immunol. 30, 3371–3379 (2000).
Liu, C. et al. The role of CCL21 in recruitment of T precursor cells to fetal thymus. Blood 105, 31–39 (2005). References 19 and 20 show the expression of chemokines in the fetal thymus. Reference 20 further examines the role of chemokines in fetal thymus colonization using a time-lapse visualization technique.
Wurbel, M. A. et al. Mice lacking the CCR9 CC-chemokine receptor show a mild impairment of early T- and B-cell development and a reduction in T-cell receptor γδ+ gut intraepithelial lymphocytes. Blood 98, 2626–2632 (2001).
Ara, T. et al. A role of CXC chemokine ligand 12/stromal cell-derived factor-1/pre-B cell growth stimulating factor and its receptor CXCR4 in fetal and adult T cell development in vivo. J. Immunol. 170, 4649–4655 (2003).
Lind, E. F., Prockop, S. E., Porritt, H. E. & Petrie, H. T. Mapping precursor movement through the postnatal thymus reveals specific microenvironments supporting defined stages of early lymphoid development. J. Exp. Med. 194, 127–134 (2001). This study shows that the adult thymus is seeded at the cortico–medullary junction and that immature thymocytes migrate outwards to the subcapsular zone.
Rossi, F. M. V. et al. Recruitment of adult thymic progenitors is regulated by P-selectin and its ligand PSGL-1. Nature Immunol. 6, 626–634 (2005). This study provides the molecular mechanism of adult thymus seeding by showing the involvement of P-selectin and PSGL1.
Fossa, D. L., Donskoya, E. & Goldschneider, I. The importation of hematogenous precursors by the thymus is a gated phenomenon in normal adult mice. J. Exp. Med. 193, 365–374 (2001).
Le Douarin, N. M. & Jotereau, F. V. Tracing of cells of the avian thymus through embryonic life in interspecific chimeras. J. Exp. Med. 142, 17–40 (1975).
Havran, W. L. & Allison, J. P. Developmentally ordered appearance of thymocytes expressing different T-cell antigen receptors. Nature 335, 443–445 (1988).
Coltey, M. et al. Analysis of the first two waves of thymus homing stem cells and their T cell progeny in chick–quail chimeras. J. Exp. Med. 170, 543–557 (1989).
Dunon, D. et al. Ontogeny of the immune system: γδ and αβ T cells migrate from thymus to the periphery in alternating waves. J. Exp. Med. 186, 977–988 (1997).
Ikuta, K. et al. A developmental switch in thymic lymphocyte maturation potential occurs at the level of hematopoietic stem cells. Cell 62, 863–874 (1990).
Weber-Arden, J., Wilbert, O. M., Kabelitz, D. & Arden, B. Vδ repertoire during thymic ontogeny suggests three novel waves of γδ TCR expression. J. Immunol. 164, 1002–1012 (2000).
Pearse, M. et al. A murine early thymocyte developmental sequence is marked by transient expression of the interleukin 2 receptor. Proc. Natl Acad. Sci. USA 86, 1614–1618 (1989).
Shinkai, Y. et al. RAG-2-deficient mice lack mature lymphocytes owing to inability to initiate V(D)J rearrangement. Cell 68, 855–867 (1992).
Radtke, F. et al. Deficient T cell fate specification in mice with an induced inactivation of Notch1. Immunity 10, 547–558 (1999).
Zúñiga-Pflücker, J. C. T-cell development made simple. Nature Rev. Immunol. 4, 67–72 (2004).
Peschon, J. J. et al. Early lymphocyte expansion is severely impaired in interleukin 7 receptor-deficient mice. J. Exp. Med. 180, 1955–1960 (1994).
von Freedem-Jeffry, U. et al. Lymphopenia in interleukin (IL)-7 gene-deleted mice identifies IL-7 as a nonredundant cytokine. J. Exp. Med. 181, 1519–1526 (1995).
Klug, D. B. et al. Interdependence of cortical thymic epithelial cell differentiation and T-lineage commitment. Proc. Natl Acad. Sci. USA 95, 11822–11827 (1998).
Klug, D. B., Carter, C., Gimenez-Conti, I. B. & Richie, E. R. Thymocyte-independent and thymocyte-dependent phases of epithelial patterning in the fetal thymus. J. Immunol. 169, 2842–2845 (2002).
Plotkin, J., Prockop, S. E., Lepique, A. & Petrie, H. T. Critical role for CXCR4 signaling in progenitor localization and T cell differentiation in the postnatal thymus. J. Immunol. 171, 4521–4527 (2003).
Misslitz, A. et al. Thymic T cell development and progenitor localization depend on CCR7. J. Exp. Med. 200, 481–491 (2004).
Benz, C., Heinzel, K. & Bleul, C. C. Homing of immature thymocytes to the subcapsular microenvironment within the thymus is not an absolute requirement for T cell development. Eur. J. Immunol. 34, 3652–3663 (2004). References 40–42 show the involvement of chemokines in the outward migration of DN thymocytes to the subcapsular zone.
Raulet, D. H., Garman, R. D., Saito, H. & Tonegawa, S. Developmental regulation of T-cell receptor gene expression. Nature 314, 103–107 (1985).
von Boehmer, H. & Fehling, H. J. Structure and function of the pre-T cell receptor. Annu. Rev. Immunol. 15, 433–452 (1997).
Irving, B. A., Alt, F. W. & Killeen, N. Thymocyte development in the absence of pre-T cell receptor extracellular immunoglobulin domains. Science 280, 905–908 (1998).
Ciofani, M. & Zúñiga-Pflücker, J. C. Notch promotes survival of pre-T cells at the β-selection checkpoint by regulating cellular metabolism. Nature Immunol. 6, 881–888 (2005).
Takahama, Y., Letterio, J. J., Suzuki, H., Farr, A. G. & Singer, A. Early progression of thymocytes along the CD4/CD8 developmental pathway is regulated by a subset of thymic epithelial cells expressing transforming growth factor β. J. Exp. Med. 179, 1495–1506 (1994).
Kisielow, P., Teh, H. S., Bluthmann, H. & von Boehmer, H. Positive selection of antigen-specific T cells in thymus by restricting MHC molecules. Nature 335, 730–733 (1988).
Jameson, S. C., Hogquist, K. A. & Bevan, M. J. Positive selection of thymocytes. Annu. Rev. Immunol. 13, 93–126 (1995).
Witt, C. M., Raychaudhuri, S., Schaefer, B., Chakraborty, A. K. & Robey, E. A. Directed migration of positively selected thymocytes visualized in real time. PLoS Biol. 3, e160 (2005).
Bousso, P., Bhakta, N. R., Lewis, R. S. & Robey, E. Dynamics of thymocyte-stromal cell interactions visualized by two-photon microscopy. Science 296, 1876–1880 (2002). Through devising in situ visualization of the thymus microenvironment with two-photon microscopy, references 50 and 51 describe the behaviour and motility of developing thymocytes.
Kim, C. H., Pelus, L. M., White, J. R. & Broxmeyer, H. E. Differential chemotactic behavior of developing T cells in response to thymic chemokines. Blood 91, 4434–4443 (1998).
Campbell, J. J., Pan, J. & Butcher, E. C. Cutting edge: developmental switches in chemokine responses during T cell maturation. J. Immunol. 163, 2353–2357 (1999).
Ueno, T. et al. CCR7 signals are essential for cortex-to-medulla migration of developing thymocytes. J. Exp. Med. 200, 493–505 (2004). This study shows the involvement of CCR7 and its ligands in the cortex-to-medulla migration of positively selected thymocytes.
Kwan, J. & Killeen, N. CCR7 directs the migration of thymocytes into the thymic medulla. J. Immunol. 172, 3999–4007 (2004).
Eggli, P., Schaffner, T., Gerber, H. A., Hess, M. W. & Cottier, H. Accessibility of thymic cortical lymphocytes to particles translocated from the peritoneal cavity to parathymic lymph nodes. Thymus 8, 129–139 1986).
Nieuwenhuis, P. et al. The transcapsular route: a new way for (self-) antigens to by-pass the blood–thymus barrier. Immunol. Today 9, 372–375 (1988).
Shores, E. W., van Ewijk, W. & Singer, A. Maturation of medullary thymic epithelium requires thymocytes expressing fully assembled CD3–TCR complexes. Int. Immunol. 6, 1393–1402 (1994).
Nasreen, M., Ueno, T., Saito, F. & Takahama, Y. In vivo treatment of class II MHC-deficient mice with anti-TCR antibody restores the generation of circulating CD4 T cells and optimal architecture of thymic medulla. J. Immunol. 171, 3394–3400 (2003).
Burkly, L. et al. Expression of relB is required for the development of thymic medulla and dendritic cells. Nature 373, 531–536 (1995).
Boehm, T., Scheu, S., Pfeffer, K. & Bleul, C. C. Thymic medullary epithelial cell differentiation, thymocyte emigration, and the control of autoimmunity require lympho-epithelial cross talk via LTβR. J. Exp. Med. 198, 757–769 (2003).
Kajiura, F. et al. NF-κB-inducing kinase establishes self-tolerance in a thymic-stroma dependent manner. J. Immunol. 172, 2067–2075 (2004).
Akiyama, T. et al. Dependence of self-tolerance on TRAF6-directed development of thymic stroma. Science 308, 248–251 (2005).
Reichert, R. A., Weissman, I. L. & Butcher, E. C. Phenotypic analysis of thymocytes that express homing receptors for peripheral lymph nodes. J. Immunol. 136, 3521–3528 (1986).
Bendelac, A., Matzinger, P., Seder, R. A., Paul, W. E. & Schwartz, R. H. Activation events during thymic selection. J. Exp. Med. 175, 731–742 (1992).
Ramsdell, F., Jenkins, M., Dinh, Q. & Fowlkes, B. J. The majority of CD4+8− thymocytes are functionally immature. J. Immunol. 147, 1779–1785 (1991).
Kyewski, B. & Derbinski, J. Self-representation in the thymus: an extended view. Nature Rev. Immunol. 4, 688–698 (2004).
Zuklys, S. et al. Normal thymic architecture and negative selection are associated with Aire expression, the gene defective in the autoimmune-polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED). J. Immunol. 165, 1976–1983 (2000).
Derbinski, J. et al. Promiscuous gene expression in thymic epithelial cells is regulated at multiple levels. J. Exp. Med. 202, 33–45 (2005).
Nagamine, K. et al. Positional cloning of the APECED gene. Nature Genet. 17, 393–398 (1997).
Aaltonen, J. et al. An autoimmune disease, APECED, caused by mutations in a novel gene featuring two PHD-type zinc-finger domains. Nature Genet. 17, 399–403 (1997).
Anderson, M. S. et al. Projection of an immunological self shadow within the thymus by the Aire protein. Science 298, 1395–1401 (2002).
Liston, A., Lesage, S., Wilson, J., Peltonen, L. & Goodnow, C. C. Aire regulates negative selection of organ-specific T cells. Nature Immunol. 4, 350–354 (2003).
Kuroda, N. et al. Development of autoimmunity against transcriptionally unrepressed target antigen in the thymus of Aire-deficient mice. J. Immunol. 174, 1862–1870 (2005).
Gallegos, A. M. & Bevan, M. J. Central tolerance to tissue-specific antigens mediated by direct and indirect antigen presentation. J. Exp. Med. 200, 1039–1049 (2004).
Anderson, M. S. et al. The cellular mechanism of Aire control of T cell tolerance. Immunity 23, 227–239 (2005).
Sakaguchi, S. Naturally arising CD4+ regulatory T cells for immunologic self-tolerance and negative control of immune responses. Ann. Rev. Immunol. 22, 531–562 (2004).
Fontenot, J. D. et al. Regulatory T cell lineage specification by the forkhead transcription factor Foxp3. Immunity 22, 329–341 (2005).
Watanabe, N. et al. Hassall's corpuscles instruct dendritic cells to induce CD4+CD25+ regulatory T cells in human thymus. Nature 436, 1181–1185 (2005).
Lieberam, I. & Forster, I. The murine β-chemokine TARC is expressed by subsets of dendritic cells and attracts primed CD4+ T cells. Eur. J. Immunol. 29, 2684–2694 (1999).
Alferink, J. et al. Compartmentalized production of CCL17 in vivo: strong inducibility in peripheral dendritic cells contrasts selective absence from the spleen. J. Exp. Med. 197, 585–599 (2003).
Chantry, D. et al. Macrophage-derived chemokine is localized to thymic medullary epithelial cells and is a chemoattractant for CD3+, CD4+, CD8low thymocytes. Blood 94, 1890–1898 (1999).
Annunziato, F. et al. Macrophage-derived chemokine and EBI1-ligand chemokine attract human thymocytes in different stage of development and are produced by distinct subsets of medullary epithelial cells: possible implications for negative selection. J. Immunol. 165, 238–246 (2000).
Chaffin, K. E. & Perlmutter, R. M. A pertussis toxin-sensitive process controls thymocyte emigration. Eur. J. Immunol. 21, 2565–2573 (1991).
Matloubian, M. et al. Lymphocyte egress from thymus and peripheral lymphoid organs is dependent on S1P receptor 1. Nature 427, 355–360 (2004). This study shows the role of S1P and its receptor in thymic export.
Allende, M. L., Dreier, J. L., Mandala, S. & Proia, R. L. Expression of the sphingosine 1-phosphate receptor, S1P1, on T-cells controls thymic emigration. J. Biol. Chem. 279, 15396–15401 (2004).
Edsall, L. C. & Spiegel, S. Enzymatic measurement of sphingosine 1-phosphate. Anal. Biochem. 272, 80–86 (1999).
Ueno, T. et al. Role for CCR7 ligands in the emigration of newly generated T lymphocytes from the neonatal thymus. Immunity 16, 205–218 (2002).
Poznansky, M. C. et al. Thymocyte emigration is mediated by active movement away from stroma-derived factors. J. Clin. Invest. 109, 1101–1110 (2002).
Kato, S. Thymic microvascular system. Microscopy Res. Tech. 38, 287–299 (1997).
Ushiki, T. A scanning electron-microscopic study of the rat thymus with special reference to cell types and migration of lymphocytes into the general circulation. Cell Tissue Res. 244, 285–298 (1986).
Michie, S. A. & Rouse, R. V. Traffic of mature lymphocytes into the mouse thymus. Thymus 13, 141–148 (1989).
Prockop, S. E. et al. Stromal cells provide the matrix for migration of early lymphoid progenitors through the thymic cortex. J. Immunol. 169, 4354–4361 (2002).
Muller, K. M., Luedecker, C. J., Udey, M. C. & Farr, A. G. Involvement of E-cadherin in thymus organogenesis and thymocyte maturation. Immunity 6, 257–264 (1997).
Vergara-Silva, A., Schaefer, K. L. & Berg, L. J. Compartmentalized Eph receptor and ephrin expression in the thymus. Mech. Dev. 119 (Suppl. 1), S225–S229 (2002).
Yanagawa, Y., Iwabuchi, K. & Onoe, K. Enhancement of stromal cell-derived factor-1α-induced chemotaxis for CD4/8 double-positive thymocytes by fibronectin and laminin in mice. Immunology 104, 43–49 (2001).
Savino, W., Mendes-da-Cruz, D. A., Silva, J. S., Dardenne, M. & Cotta-de-Almeida, V. Intrathymic T-cell migration: a combinatorial interplay of extracellular matrix and chemokines? Trends Immunol. 23, 305–313 (2002).
Gill, J. et al. Thymic generation and regeneration. Immunol. Rev. 195, 28–50 (2003).
Barry, T. S., Jones, D. M., Richter, C. B. & Haynes, B. F. Successful engraftment of human postnatal thymus in severe combined immune deficient (SCID) mice: differential engraftment of thymic components with irradiation versus anti-asialo GM-1 immunosuppressive regimens. J. Exp. Med. 173, 167–180 (1991).
Poznansky, M. C. et al. Efficient generation of human T cells from a tissue-engineered thymic organoid. Nature Biotechnol. 18, 729–734 (2000).
Bhandoola, A. & Sambandam, A. From stem cell to T cell: one route or many? Nature Rev. Immunol. 6, 117–126 (2006).
Kawamoto, H., Ohmura, K. & Katsura, Y. Presence of progenitors restricted to T, B, or myeloid lineage, but absence of multipotent stem cells, in the murine fetal thymus. J. Immunol. 161, 3799–3802 (1998).
Rodewald, H. R., Kretzschmar, K., Takeda, S., Hohl, C. & Dessing, M. Identification of pro-thymocytes in murine fetal blood: T lineage commitment can precede thymus colonization. EMBO J. 13, 4229–4240 (1994).
Harman, B. C. et al. T/B lineage choice occurs prior to intrathymic Notch signaling. Blood 106, 886–892 (2005).
Porritt, H. E. et al. Heterogeneity among DN1 prothymocytes reveals multiple progenitors with different capacities to generate T cell and non-T cell lineages. Immunity 20, 735–745 (2004).
Sambandam, A. et al. Notch signaling controls the generation and differentiation of early T lineage progenitors. Nature Immunol. 6, 663–670 (2005).
Benz, C. & Bleul, C. C. A multipotent precursor in the thymus maps to the branching point of the T versus B lineage decision. J. Exp. Med. 202, 21–31 (2005).
Taylor, J. R. et al. Expression and function of chemokine receptors on human thymocytes: implications for infection by human immunodeficiency virus type 1. J. Virol. 75, 8752–8760 (2001).
Wurbel, M. A. et al. The chemokine TECK is expressed by thymic and intestinal epithelial cells and attracts double- and single-positive thymocytes expressing the TECK receptor CCR9. Eur. J. Immunol. 30, 262–271 (2000).
Carramolino, L. et al. Expression of CCR9 β-chemokine receptor is modulated in thymocyte differentiation and is selectively maintained in CD8+ T cells from secondary lymphoid organs. Blood 97, 850–857 (2001).
Norment, A. M., Bogatzki, L. Y., Gantner, B. N. & Bevan, M. J. Murine CCR9, a chemokine receptor for thymus-expressed chemokine that is up-regulated following pre-TCR signaling. J. Immunol. 164, 639–648 (2000).
Uehara, S., Song, K., Farber, J. M. & Love, P. E. Characterization of CCR9 expression and CCL25/thymus-expressed chemokine responsiveness during T cell development: CD3highCD69+ thymocytes and γδ TCR+ thymocytes preferentially respond to CCL25. J. Immunol. 168, 134–142 (2002).
Youn, B. S., Kim, C. H., Smith, F. O. & Broxmeyer, H. E. TECK, an efficacious chemoattractant for human thymocytes, uses GPR-9–6/CCR9 as a specific receptor. Blood 94, 2533–2536 (1999).
Zaitseva, M. et al. Stromal-derived factor 1 expression in the human thymus. J. Immunol. 168, 2609–2617 (2002).
Acknowledgements
I would like to thank current and previous members of the laboratory, especially T. Ueno and C. Liu, for their discussion and experiments on thymocyte traffic and thymic micro environments. I also would like to thank M. Kubo and F. Saito for excellent and skillful assistance in the study. Continuous discussions with many colleagues, including G. Hollander, R. Boyd, H. Petrie, G. Anderson, W. van Ewijk, H. Kawamoto, T. Ushiki and A. Singer, have made essential contributions to the framework of the idea reviewed here. Financial support by the MEXT Grant-in-Aid for scientific research and the JSPS Core-to-Core Program is acknowledged.
Author information
Authors and Affiliations
Ethics declarations
Competing interests
The author declares no competing financial interests.
Related links
Glossary
- Thymic primordium
-
The primordium refers to an organ or tissue in its earliest recognizable stage of development. The primordium of the thymus is generated at the ventral aspect of the third pharyngeal pouch as early as embryonic day 10.5 in mice.
- Thymic parenchyma
-
The parenchyma refers to the functional part of an organ. The parenchyma of the thymus is surrounded by the capsule, the trabeculae and the perivascular spaces.
- Two-photon laser fluorescence microscopy
-
A fluorescence-imaging technique that takes advantage of the fact that fluorescent molecules can absorb two photons simultaneously during excitation before they emit light. This technique greatly reduces photodamage of living specimens, improves tissue penetration depth, allows the distinct separation between excitation and emission wavelengths, and confines the excitation to a discrete focal point.
- Interstitial fluid
-
The fluid in the spaces between cells and tissues, outside the lymphatic or cardiovascular systems. Its composition is similar to plasma and lymph.
- Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy
-
(APECED or autoimmune polyendocrine syndrome type 1). APECED is characterized by the presence of two of three clinical symptoms: Addison's disease and/or hypoparathyroidism and/or chronic mucocutaneous candidiasis. It is caused by a mutation in the gene autoimmune regulator (AIRE).
- Hassall's corpuscles
-
Small clusters or concentric whorls of stratified keratinizing epithelium in the thymic medulla, possibly involved in the negative selection of thymocytes, the generation of regulatory T cells and/or undergoing apoptosis themselves. They are found clearly in the human thymus, but are unclear in the mouse thymus.
- G-protein-coupled receptor
-
(GPCR). A receptor that is composed of seven membrane-spanning helical segments. These receptors associate with G-proteins, which are a family of trimeric intracellular-signalling proteins with common β- and γ-chains, and one of several α-chains. The α-chain determines the nature of the signal that is transmitted from a ligand-occupied GPCR to downstream effector systems.
Rights and permissions
About this article
Cite this article
Takahama, Y. Journey through the thymus: stromal guides for T-cell development and selection. Nat Rev Immunol 6, 127–135 (2006). https://doi.org/10.1038/nri1781
Issue Date:
DOI: https://doi.org/10.1038/nri1781
This article is cited by
-
How autoreactive thymocytes differentiate into regulatory versus effector CD4+ T cells after avoiding clonal deletion
Nature Immunology (2023)
-
T cells in health and disease
Signal Transduction and Targeted Therapy (2023)
-
Mesenchymal stromal cells in the thymus
Inflammation and Regeneration (2022)
-
Radiation inducible MafB gene is required for thymic regeneration
Scientific Reports (2021)
-
T cell regeneration after immunological injury
Nature Reviews Immunology (2021)