The TCR repertoire of a normal animal is shaped in the thymus by ligand-specific positive- and negative-selection events. These processes are believed to be determined at the single-cell level primarily by the affinity of the TCR-ligand interactions. The relationships among all the variables involved are still unknown due to the complexity of the interactions and the lack of quantitative analys...

We here describe intercellular calcium waves as a novel form of cellular communication among thymic epithelial cells. We first characterized the mechanical induction of intercellular calcium waves in different thymic epithelial cell preparations: cortical 1-4C18 and medullary 3-10 thymic epithelial cell lines and primary cultures of thymic "nurse" cells. All thymic epithelial preparations respo...

Laminin 5 (alpha3beta3gamma2) distribution in the human thymus was investigated by immunofluorescence on frozen sections with anti-alpha3, -beta3, and -gamma2 mAbs. In addition to a linear staining of subcapsular basal laminae, the three mAbs give a disperse staining in the parenchyma restricted to the medullary area on a subset of stellate epithelial cells and vessel structures. We also found ...

T cell development in the thymus involves a series of TCR-mediated control points including TCR-beta selection and positive and negative selection. Approximately half of the thymic sojourn is spent in the medulla, where thymocytes undergo final maturation before emigrating to the periphery. Although it is acknowledged that thymic emigration is an active process, relatively little is known about...

Medullary, peanut agglutinin-negative (PNA-), thymocytes were activated in vitro with either exogenous interleukin 1 (IL-1) or accessory cells. T cell blasts from these cultures were subsequently fused to BW5147 to generate thymocyte hybridomas. Fusion frequencies similar to those obtained with peripheral T lymphocytes were observed. A high frequency of these hybrids are triggered to produce IL...

Thymic size and T-cell function decrease with age, and it has not yet been possible to totally reverse this thymic atrophy and completely restore T-cell-dependent immune functions. In this study, GH3 pituitary adenoma cells, which secrete growth hormone and prolactin, were implanted subcutaneously into 16- and 22-month-old female Wistar-Furth rats and the rats were sacrificed approximately 2 mo...

The present study investigated the potential role of stromal cell-derived factor 1 (SDF-1) in human intrathymic T-cell differentiation. Results show that SDF-1 is produced by human thymic epithelial cells from the subcapsular and medullary areas, and its receptor, CXCR4, is up-regulated on CD34(+) precursor cells committed to the T-cell lineage. Chimeric human-mouse fetal thymus organ culture (...

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 ...

Primer T he mammalian immune system is tightly controlled to be activated by infectious agents but not by self. The ability to respond to the universe of potential antigens is mediated by a repertoire of T and B lymphocytes with an extraordinary range of specificities. The diversity of T and B lymphocyte antigen receptors is generated by completely random rearrangement of gene segments. Thus, t...

Although the role that Autoimmune Regulator (Aire) plays in the induction of central tolerance is well known, the precise cellular and molecular mechanisms are still unclear and debated. In the prevailing view, Aire serves mainly as a direct inducer of tissue-specific antigens. However, there is a growing amount of evidence suggesting that Aire modulates the differentiation program of medullary...