title: Antigen-independent maturation of CD2, CD11a/CD18, CD44, and CD58 expression on thymic emigrants in fetal and postnatal sheep.
abstract: We have compared the expression of CD2, CD11a/CD18, CD44, and CD58 and alpha beta and gamma delta T cells emigrating from the fetal and postnatal thymus. We report that both gamma delta and the CD4+CD8- and CD4-CD8+ subsets of alpha beta T cells express mature levels of the adhesion molecules CD11a/CD18, CD44, and CD58 upon emigration from the thymus. Whereas CD44 is up-regulated on gamma delta + thymocytes prior to export, down-regulation of both CD11a/CD18 and CD58 occurs prior to emigration from the thymus, suggesting that down-regulation of these molecules may be a final maturational step taken by developing gamma delta T cells before their export from the thymus. In contrast, there is continued up-regulation of CD2 on gamma delta and alpha beta T cells upon emigration from the thymus and as they move into the mature peripheral T-cell pool. There was also a marked reduction in the number of CD2+ gamma delta T cells exported during fetal development that was associated with a marked reduction in the percentage of CD2+ gamma delta thymocytes exported. The postthymic maturation of CD2 and the other changes in adhesion-molecule expression appear to be independent of extrinsic antigen, as the same changes were observed in the antigen-free environment of the fetus as in the postnatal lamb, which has been exposed to extrinsic antigen. It thus appears that these changes in adhesion-molecule expression are as a result of the normal maturation pathway from a developing thymocyte to a mature peripheral T cell.
authors.affiliation: Laboratory for Foetal and Neonatal Immunology, University of Melbourne, Parkville, VIC, Australia.
authors.forename: D A
authors.initials: DA
authors.lastname: Witherden
authors.forename: N J
authors.initials: NJ
authors.lastname: Abernethy
authors.forename: W G
authors.initials: WG
authors.lastname: Kimpton
authors.forename: R N
authors.initials: RN
authors.lastname: Cahill
mesh_terms: D000818:Animals; D018821:CD18 Antigens / Q000378:metabolism; D018801:CD2 Antigens / Q000378:metabolism; D018968:CD58 Antigens / Q000378:metabolism; D002454:Cell Differentiation / Q000276:immunology; D002465:Cell Movement; D005260:Female; D005333:Fetus / Q000166:cytology* / Q000276:immunology*; D018960:Hyaluronan Receptors / Q000378:metabolism; D016169:Lymphocyte Function-Associated Antigen-1 / Q000378:metabolism; D011247:Pregnancy; D012756:Sheep; D016176:T-Lymphocyte Subsets / Q000166:cytology / Q000276:immunology* / Q000502:physiology; D013950:Thymus Gland / Q000166:cytology* / Q000196:embryology / Q000276:immunology*
chemical_list: D018821:CD18 Antigens; D018801:CD2 Antigens; D018968:CD58 Antigens; D018960:Hyaluronan Receptors; D016169:Lymphocyte Function-Associated Antigen-1