title: Thymic OX40 expression discriminates cells undergoing strong responses to selection ligands.
abstract: OX40 is a member of the TNF receptor family expressed on activated and regulatory T (Treg) cells. Using an Ox40-cre allele for lineage marking, we found that a subpopulation of naive T cells had also previously expressed OX40 in the thymus. Ox40-cre was induced in a small fraction of thymocytes that were OX40(+), some of which were CD25(high) Treg cell precursors. Thymic OX40 expression distinguished cells experiencing a strong signaling response to positive selection. Naive T cells that had previously expressed OX40 demonstrated a partially activated phenotype that was distinct from that of most naive T cells. The results are consistent with the selection of Treg cells and a minor subpopulation of naive T cells being dependent on strong signaling responses to thymic self ligands.
authors.affiliation: Department of Microbiology and Immunology and.
authors.forename: Mark
authors.initials: M
authors.lastname: Klinger
authors.forename: Joong Kyu
authors.initials: JK
authors.lastname: Kim
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Chmura
authors.forename: Andrea
authors.initials: A
authors.lastname: Barczak
authors.forename: David J
authors.initials: DJ
authors.lastname: Erle
authors.forename: Nigel
authors.initials: N
authors.lastname: Killeen