title: Developmentally regulated expression of the beta 4 integrin on immature mouse thymocytes.
abstract: Integrins are a superfamily of alpha beta heterodimers, most of which serve as cell surface receptors for extracellular matrix proteins. In this report, we demonstrate that the recently described alpha 6 beta 4 integrin, previously thought to be limited to epithelial cells and Schwann cells, is expressed on immature mouse thymocytes. The presence of alpha 6 beta 4 is controlled by regulation of beta 4 expression, because alpha 6 was expressed by virtually all cells examined, paired with the beta 1 integrin chain to form VLA-6. During fetal ontogeny, beta 4 was highly expressed by 35% of day-13 thymocytes, 75% of day-14 to -15 thymocytes, then rapidly declined to low levels by birth. In neonates and adults, beta 4 expression was highest on CD4- CD8- CD3- and TCR(+)-gamma delta subsets. Correlation of IL-2R, CD44 and beta 4 on CD4- CD8- thymocytes revealed maximal levels on the intermediate CD44- IL-2R+ subset. Most CD4- CD8+ TCR- thymocytes and a significant fraction of CD4+ CD8+ thymocytes were beta 4lo, whereas the most mature J11d- single positive thymocytes were beta-4. Overall, down-regulation of beta 4 was associated with up-regulation of CD4, CD8, and CD3 in the thymus. alpha 6 beta 4 was undetectable on fetal liver or bone marrow cells, lymphocytes from lymph node, spleen, or blood, and mitogen-activated splenic T cells cultured up to 10 wk with IL-2. The data suggest that alpha 6 beta 4 is up-regulated after pro-T cells enter the thymus and may have a thymus-specific function for T cells. The developmentally regulated pattern of expression and the prominence of alpha 6 beta 4 on day-13 to -16 fetal and adult CD4- CD8- CD3- thymocytes further suggest this unusual integrin may play a role in early T cell development, including stages before acquisition of the TCR.
authors.affiliation: Biological Resources Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892.
authors.forename: S
authors.initials: S
authors.lastname: Wadsworth
authors.forename: M J
authors.initials: MJ
authors.lastname: Halvorson
authors.forename: J E
authors.initials: JE
authors.lastname: Coligan
mesh_terms: D000367:Age Factors; D000818:Animals; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis; D017252:CD3 Complex; D015704:CD4 Antigens / Q000032:analysis; D016827:CD8 Antigens / Q000032:analysis; D005260:Female; D005333:Fetus / Q000276:immunology; D016023:Integrins / Q000032:analysis* / Q000276:immunology / Q000502:physiology; D051379:Mice; D011233:Precipitin Tests; D011247:Pregnancy; D011948:Receptors, Antigen, T-Cell / Q000032:analysis; D015375:Receptors, Interleukin-2 / Q000032:analysis; D016201:Receptors, Lymphocyte Homing / Q000032:analysis; D016176:T-Lymphocyte Subsets / Q000276:immunology; D013601:T-Lymphocytes / Q000737:chemistry* / Q000276:immunology
chemical_list: D000945:Antigens, Differentiation, T-Lymphocyte; D017252:CD3 Complex; D015704:CD4 Antigens; D016827:CD8 Antigens; D016023:Integrins; D011948:Receptors, Antigen, T-Cell; D015375:Receptors, Interleukin-2; D016201:Receptors, Lymphocyte Homing