title: Correlation between recent thymic emigrants and CD31+ (PECAM-1) CD4+ T cells in normal individuals during aging and in lymphopenic children.
abstract: CD31(+)CD45RA(+)RO(-) lymphocytes contain high numbers of T cell receptor circle (TREC)-bearing T cells; however, the correlation between CD31(+)CD4(+) lymphocytes and TREC during aging and under lymphopenic conditions has not yet been sufficiently investigated. We analyzed TREC, telomere length and telomerase activity within sorted CD31(+) and CD31(-) CD4(+) lymphocytes in healthy individuals from birth to old age. Sorted CD31(+)CD45RA(+)RO(-) naive CD4(+) lymphocytes contained high TREC numbers, whereas CD31(+)CD45RA(-)RO(+) cells (comprising < or =5% of CD4(+) cells during aging) did not contain TREC. CD31(+) overall CD4(+) cells remained TREC rich despite an age-related tenfold reduction from neonatal (100 : 1000) to old age (10 : 1000). Besides a high TREC content, CD31(+)CD45RA(+)RO(-)CD4(+) cells exhibited significantly longer telomeres and higher telomerase activity than CD31(-)CD45RA(+)RO(-)CD4(+) cells, suggesting that CD31(+)CD45RA(+)RO(-)CD4(+) cells represent a distinct population of naive T cells with particularly low replicative history. To analyze the value of CD31 in lymphopenic conditions, we investigated six children after allogeneic hematopoietic stem cell transplantation (HSCT). Reemerging overall CD4(+) as well as naive CD45RA(+)RO(-)CD4(+) cells predominantly expressed CD31 and correlated well with the recurrence of TREC 5-12 months after HSCT. Irrespective of limitations in the elderly, CD31 is an appropriate marker to monitor TREC-rich lymphocytes essentially in lymphopenic children after HSCT.
authors.affiliation: Division of Immunology/Hematology/BMT, University Children's Hospital, Zürich, Switzerland.
authors.forename: Sonja
authors.initials: S
authors.lastname: Junge
authors.forename: Barbara
authors.initials: B
authors.lastname: Kloeckener-Gruissem
authors.forename: Romain
authors.initials: R
authors.lastname: Zufferey
authors.forename: Andre
authors.initials: A
authors.lastname: Keisker
authors.forename: Bettina
authors.initials: B
authors.lastname: Salgo
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Fauchere
authors.forename: Franziska
authors.initials: F
authors.lastname: Scherer
authors.forename: Tarek
authors.initials: T
authors.lastname: Shalaby
authors.forename: Michael
authors.initials: M
authors.lastname: Grotzer
authors.forename: Ulrich
authors.initials: U
authors.lastname: Siler
authors.forename: Reinhard
authors.initials: R
authors.lastname: Seger
authors.forename: Tayfun
authors.initials: T
authors.lastname: Güngör
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D002648:Child; D002675:Child, Preschool; D005434:Flow Cytometry; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008231:Lymphopenia / Q000276:immunology*; D008875:Middle Aged; D010957:Plasmids; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000276:immunology / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016176:T-Lymphocyte Subsets / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D019098:Telomerase / Q000378:metabolism; D016615:Telomere / Q000378:metabolism; D013950:Thymus Gland / Q000166:cytology / Q000254:growth & development
chemical_list: D019408:Platelet Endothelial Cell Adhesion Molecule-1; D019098:Telomerase