Wnt signaling is essential for T cell development in the thymus, but the stages in which it occurs and the molecular mechanisms underlying Wnt responsiveness have remained elusive. Here we examined Wnt signaling activity in both human and murine thymocyte populations by determining beta-catenin levels, Tcf-reporter activation and expression of Wnt-target genes. We demonstrate that Wnt signaling...

The interaction of peanut agglutinin (PNA) with human thymocytes, peripheral blood lymphocytes, and peripheral blood cells of various types of leukemia was investigated by using fluorescein isothiocyanate-conjugated PNA. The majority of human thymocytes (60-80%) bind the lectin. The major subpopulation of thymocytes that is PNA-positive was separated from the PNA-negative cells by differential ...

Signaling through the Notch pathway plays an essential role in inducing T-lineage commitment and promoting the maturation of immature thymocytes. Using an in vitro culture system, we show that 2 different classes of Notch ligands, Jagged1 or Delta1, transmit distinct signals to T-cell progenitors. OP9 stromal cells expressing either Jagged1 or Delta1 inhibit the differentiation of DN1 thymocyte...

Chemokines regulate leukocytes trafficking in normal and inflammation conditions. Thymus-seeding progenitors are made in bone marrow and migrate to the thymus where they undergo their maturation to antigen-specific T cells. Immature T cells are in thymic cortex, while mature thymocytes are in medulla. Chemokines may be important for homing of thymus-seeding progenitors, and/or differential thym...

Thymic stromal cells play important roles in thymocyte differentiation and selection. Thymic nurse cells (TNC) are thymic epithelial stromal cells that envelop two to 200 CD4+CD8+ thymocytes (TNC-T). The mechanism by which TNC complexes form and their role in thymocyte development are unknown. TNC have been implicated as specialized microenvironments for proliferation, positive selection, negat...

Human herpesvirus 6 (HHV-6) is a potentially immunosuppressive agent that may act as a cofactor in the progression of AIDS. Here, we describe the first small animal model of HHV-6 infection. HHV-6 subgroup A, strain GS, efficiently infected the human thymic tissue implanted in SCID-hu Thy/Liv mice, leading to the destruction of the graft. Viral DNA was detected in Thy/Liv implants by quantitati...

The mouse thymus was assessed for its ability to produce steroids. Cultured thymic non-T cells produced soluble pregnenolone and deoxycorticosterone, and immunohistochemistry demonstrated steroidogenic enzymes in radioresistant thymic epithelial cells but not in thymocytes. Inhibition of thymic corticosterone production or blockade of the glucocorticoid receptor with RU-486 resulted in enhanced...

The random addition of "N nucleotides" by terminal deoxynucleotidyltransferase (TdT) is an important component of the diversity of T-cell receptor genes. We have investigated the expression of TdT during thymocyte differentiation and thymus ontogeny. TdT gene transcripts are confined to immature thymocytes of the cortex, being down-regulated concomitantly with recombination-activating gene tran...

Three distinct immature T-cell acute lymphoblastic leukemia entities have been described including cases that express an early T-cell precursor immunophenotype or expression profile, immature MEF2C-dysregulated T-cell acute lymphoblastic leukemia cluster cases based on gene expression analysis (immature cluster) and cases that retain non-rearranged TRG@ loci. Early T-cell precursor acute lympho...

background: there is accumulating evidence that a polyphenol present in olive oil, oleuropein, has antioxidant, anti-inflammatory and anti-apoptotic effects. this study aimed at determining the anti-apoptotic effect of oleuropein (ole) on dexamethasone-induced apoptosis of mouse thymocytes. method: mice were randomly divided to four groups as follow: dexamethasone (dex)-treated group (20 mg/kg;...