title: Combined TCRG and TCRA TREC analysis reveals increased peripheral T-lymphocyte but constant intra-thymic proliferative history upon ageing.
abstract: T-cell receptor (TCR) repertoire diversity, thymic output, clonal size and peripheral T-lymphocyte numbers largely depend on intra-thymic and post-thymic T-lymphocyte proliferation. However, quantitative insight into thymocyte and T-lymphocyte proliferation is still lacking. We developed a new TCRG-based TCR excision circle (TREC) assay, the Vγ-Jγ TREC assay, which we used together with an adjusted δREC-ψJα TREC assay to quantify the proliferative history of human thymocyte and T-lymphocyte subpopulations from children and adults. This revealed that thymocytes undergo ∼6-8 intra-thymic cell divisions from the double negative (DN) 3 developmental stage onwards, which appeared independent of age. Thus thymocyte proliferation after the DN3 developmental stages is stable and therefore not contributing to the reduced thymic output upon ageing. Cord blood naive T lymphocytes had already undergone ∼2-3 post-thymic cell divisions, which increased to ∼6-7 cell divisions in naive T lymphocytes of middle-aged adults, indicating the importance of homeostatic naive T-lymphocyte proliferation from a young age onwards in the maintenance of peripheral T-lymphocyte numbers. In conclusion, our data provide quantitative insight into the proliferative history of thymocyte and T-lymphocyte subpopulations and alterations herein upon ageing. This novel TREC assay approach could prove valuable in immune status monitoring in a variety of conditions.
authors.affiliation: Department of Immunology, Erasmus MC, University Medical Center, Rotterdam, The Netherlands.
authors.forename: Kim
authors.initials: K
authors.lastname: van der Weerd
authors.forename: Willem A
authors.initials: WA
authors.lastname: Dik
authors.forename: Benjamin
authors.initials: B
authors.lastname: Schrijver
authors.forename: Ad J J C
authors.initials: AJ
authors.lastname: Bogers
authors.forename: Alexander P W M
authors.initials: AP
authors.lastname: Maat
authors.forename: Francien H
authors.initials: FH
authors.lastname: van Nederveen
authors.forename: P Martin
authors.initials: PM
authors.lastname: van Hagen
authors.forename: Jacques J M
authors.initials: JJ
authors.lastname: van Dongen
authors.forename: Anton W
authors.initials: AW
authors.lastname: Langerak
authors.forename: Frank J T
authors.initials: FJ
authors.lastname: Staal
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging / Q000235:genetics* / Q000276:immunology* / Q000473:pathology; D049109:Cell Proliferation; D002648:Child; D002675:Child, Preschool; D015332:Gene Rearrangement, alpha-Chain T-Cell Antigen Receptor; D015334:Gene Rearrangement, gamma-Chain T-Cell Antigen Receptor; D019673:Genes, T-Cell Receptor alpha; D019675:Genes, T-Cell Receptor gamma; D005821:Genetic Techniques; D006801:Humans; D007231:Infant, Newborn; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D016176:T-Lymphocyte Subsets / Q000166:cytology / Q000276:immunology; D013601:T-Lymphocytes / Q000166:cytology* / Q000276:immunology*; D013950:Thymus Gland / Q000166:cytology / Q000276:immunology