Trafficking from the bone marrow to the thymus: a prerequisite for thymopoiesis.
T-cell development in the thymus requires periodic importation of hematopoietic progenitors from the bone marrow. Such thymus settling progenitors arise from hematopoietic stem cells (HSCs) that are retained in a specific bone marrow microenvironmental niche. Vacation of this niche is required for HSC proliferation and differentiation into downstream progenitors. In order to reach the thymus, progenitors must then be mobilized from bone marrow to blood. Finally, progenitors in blood must settle in the thymus. Here we review signals and molecular interactions that are likely to play a role in trafficking from the bone marrow to the thymus, focusing on how these interactions may regulate which progenitors physiologically contribute to thymopoiesis.
Schwarz
Benjamin A
BA
Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6082, USA.
Bhandoola
Avinash
A
D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology*; D015815:Cell Adhesion Molecules / Q000378:metabolism; D002465:Cell Movement; D049109:Cell Proliferation; D018925:Chemokines / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000378:metabolism; D006801:Humans; D038041:Lymphopoiesis; D018448:Models, Immunological; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000166:cytology*; D013950:Thymus Gland / Q000166:cytology* / Q000378:metabolism
D015815:Cell Adhesion Molecules; D018925:Chemokines; D016207:Cytokines