title: Ontogeny of T cell receptors in the chicken thymus.
abstract: A panel of murine mAb against chicken TCR and associated molecules was used to study the ontogeny of T cells. The intrathymic maturation of the TCR-gamma delta, (TCR-1) and TCR-alpha beta (TCR-2) sublineages was the focus of these studies employing immunoperoxidase staining of tissue sections and immunofluorescence analysis of cell suspensions. The first CD3+ cells appeared in the thymus on embryonic day 9 (E9) when the CD3 Ag was restricted to the cytoplasm. In tissue sections, both TCR-1+ and TCR-2+ cells were observed on E12, whereas only the TCR-1 cells were identifiable by surface immunofluorescence. On the next day, when a discrete thymic medullary region was first recognizable, the TCR-1 cells were present in both cortex and medulla. Two days later (E15), TCR-1 cells were found in the spleen. Surface TCR-2+ cells did not appear until E14, began to migrate in to the medulla on E17, and appeared in the spleen on E19. The first TCR-1 cells thus move quickly through this maturational pathway, whereas TCR-2 cells undergo a prolonged developmental period in the cortex. While most TCR-1+ cells were CD4-CD8-, a minor subpopulation (5 to 15%) were CD4-CD8+, and less than 1% were CD4+CD8+. In contrast, immature TCR-2+ thymocytes in the cortex were predominantly CD4+CD8+, whereas cells expressing a higher density of the CD3/TCR-2 complex were either CD4+CD8- or CD4-CD8+ and were localized in the thymic medulla. In the medulla of the mature thymus, the TCR-1+ cells preferentially occupy the cortico-medullary junction and form small aggregates around vessels. TCR-2+ cells were less frequent in these areas of TCR-1 accumulation. The thymic ontogeny and, by implication, the selection of the receptor repertoire thus differs substantially for these two TCR isotypes.
authors.affiliation: Department of Pathology, University of Alabama, Birmingham 35294.
authors.forename: R P
authors.initials: RP
authors.lastname: Bucy
authors.forename: C H
authors.initials: CH
authors.lastname: Chen
authors.forename: M D
authors.initials: MD
authors.lastname: Cooper
mesh_terms: D000367:Age Factors; D000818:Animals; D000945:Antigens, Differentiation, T-Lymphocyte / Q000378:metabolism; D017252:CD3 Complex; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology; D002454:Cell Differentiation; D002465:Cell Movement; D002642:Chick Embryo; D002645:Chickens; D005455:Fluorescent Antibody Technique; D007124:Immunoenzyme Techniques; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism*; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology; D013950:Thymus Gland / Q000166:cytology / Q000196:embryology / Q000254:growth & development*
chemical_list: D000945:Antigens, Differentiation, T-Lymphocyte; D017252:CD3 Complex; D011948:Receptors, Antigen, T-Cell