title: Alpha 6 integrins participate in pro-T cell homing to the thymus.
abstract: During embryogenesis, colonization of the thymic rudiment by hemopoietic progenitor cells depends on the adhesion of these cells to the jugular endothelium. Previously, we showed that progenitor T cells (pro-T cells) interact with alpha 6 integrins present on vascular endothelium. Here, we demonstrate that anti-alpha 6 integrin antibodies reduced the number of thymocytes up to 80% in a congenic mouse model for thymus colonization by pro-T cells. In organotypic thymus cultures, the anti-alpha 6 integrin antibodies did not influence T cell development and proliferation. From this, we conclude that alpha 6 integrin participates in thymus homing. During mouse thymus ontogeny, alpha 6 integrin mRNA and protein expression was found as early as day 10 of development; at day 11, perithymic endothelial cells were alpha 6 integrin positive. Two alpha 6 integrin mRNA exist which are produced by alternative exon usage. The longer form, alpha 6 integrin, predominates during early embryonic stages, while the shorter alpha 6A form was present later during development. Although alpha 6 integrins can be displayed by immature thymocytes, strongest expression was found on intra- and perithymic vascular endothelium. These data suggest that alpha 6 integrins are involved in the homing of pro-T cells to the developing thymus by mediating adhesion of pro-T cells to the vascular endothelium.
authors.affiliation: Basel Institute for Immunology, Switzerland.
authors.forename: P
authors.initials: P
authors.lastname: Ruiz
authors.forename: M V
authors.initials: MV
authors.lastname: Wiles
authors.forename: B A
authors.initials: BA
authors.lastname: Imhof
mesh_terms: D000818:Animals; D001483:Base Sequence; D002465:Cell Movement; D017931:DNA Primers / Q000737:chemistry; D005260:Female; D005434:Flow Cytometry; D015870:Gene Expression; D016023:Integrins / Q000502:physiology*; D008213:Lymphocyte Activation; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D009924:Organ Culture Techniques; D012333:RNA, Messenger / Q000235:genetics; D016201:Receptors, Lymphocyte Homing; D013601:T-Lymphocytes / Q000166:cytology*; D013950:Thymus Gland / Q000166:cytology / Q000196:embryology* / Q000276:immunology
chemical_list: D017931:DNA Primers; D016023:Integrins; D012333:RNA, Messenger; D016201:Receptors, Lymphocyte Homing