A key role of the thymic medulla is to negatively select autoreactive CD4(+) and CD8(+) thymocytes, a process important for T cell tolerance induction. However, the involvement of the thymic medulla in other aspects of αβ T cell development, including the generation of Foxp3(+) natural regulatory T cells (nTreg cells) and the continued maturation of positively selected conventional αβ T cells, ...

After positive selection and lineage commitment, the TCR alphabeta+ CD4/CD8 SP medullary thymocytes migrate into and reside in thymic medulla, where they undergo an ordered program of late stage of T cell functional maturation and negative selection to delete self-reactive clones by apoptosis. Accomplishment of this final differentiation pathway, a physiological T cell repertoire is formed: T c...

Human thymocytes and peripheral blood lymphocytes were separated on the basis of density on Percoll gradients and the different cell populations tested regarding DNA synthesis after addition of mercuric chloride. Thymocytes with a density of 1.065-1.067 g/ml and peripheral blood lymphocytes with a density of 1.063-1.065 g/ml were maximally stimulated with mercuric chloride as well as with mitog...

A critical process during thymic development of the T cell repertoire is the induction of self-tolerance. Tolerance in developing T cells is highly dependent on medullary thymic epithelial cells (mTEC), and mTEC development in turn requires signals from mature single-positive thymocytes, a bidirectional relationship termed thymus crosstalk. We show that CD28-CD80/86 and CD40-CD40L costimulatory...

Dendritic cells (DCs) play a significant role in establishing self-tolerance through their ability to present self-antigens to developing T cells in the thymus. DCs are predominantly localized in the medullary region of thymus and present a broad range of self-antigens, which include tissue-restricted antigens expressed and transferred from medullary thymic epithelial cells, circulating antigen...

A series of monoclonal antibodies were used to study the intrathymic distribution of T cell-specific antigens, Ia antigens, and beta 2-microglobulin in frozen sections of human thymus by immunofluorescence and immunoperoxidase techniques. Most of the cortical thymocytes reacted with anti-T4, anti-T5, anti-T6, anti-T8, and anti-T10 antibodies, thus indicating coexpression of multiple antigens on...

A minor subpopulation of adult murine thymocytes (less than 5%) that is Lyt-2-, L3T4-, and expresses low levels of Ly-1 (designated dLy-1 [dull] thymocytes) has been identified, isolated, and characterized. This study assesses the differentiation potential of dLy-1 thymocytes in the thymus in vivo. Using multiparameter flow cytometry, radiation chimeras of C57BL/6 mice congenic at the Ly-1 or L...

Bone marrow progenitors migrate to the thymus, where they proliferate and differentiate into immunologically competent T cells. In this report we show that mice transgenic for SV40 T and t antigens under the control of the L-pyruvate kinase promoter develop, in a first step, thymic hyperplasia of both thymocytes and epithelial cells. Morphological studies (histology, immunohistolabeling and ele...

We previously established three mouse cell lines (Aire(+)TEC1, Aire(+)TEC2 and Aire(+)DC) from the medullary thymic epithelial cells (mTECs) and dendritic cells (mDCs). These cells constitutively expressed "autoimmune regulator (Aire) gene" and they exhibited various features of self antigen-presenting cells (self-APCs) present in the thymic medullary region. Here, we confirmed our previous obs...

We have examined infection of the thymus during congenitally acquired chronic lymphocytic choriomeningitis virus (LCMV) infection of mice, a classic model of antigen-specific T-cell tolerance. Our results show that (i) infection starts at the fetal stage and is maintained throughout adulthood, and (ii) this chronic infection of the thymus can be eliminated by transfer of virus-specific cytotoxi...