Origin of Thy-1+ dendritic epidermal cells of adult mice from fetal thymic precursors

Article Abstract:

Dendritic cells are thought to play an important role in the initiation of immune responses. Although the dendritic epidermal cells (dEC) express the Thy-1 antigen, which is found on T-cells which mature in the thymus, it was not thought that the thymus played a role in the development of the dEC. This was due to the fact that Thy-1-positive dEC are found in the skin of nude mice, which have no thymus and have a correspondingly deficient cellular immune response. It was found, however, that the dEC of nude mice did not express the T-cell receptor (TCR) on the cell surface, and the material inside the cell was in a primitive form. In order to find out if the thymus does indeed play a role in the development of these cells, fetal thymus was implanted into adult nude mice. Dendritic epidermal cells with adult TCR expression appeared in the skin. Although this demonstrates that the thymus is sufficient for the production of these cells, it does not distinguish whether these cells migrated from the thymus, or whether the thymus merely stimulates in some way the bone marrow cells on their way to the skin. This question was resolved using the two genetic forms of the Thy-1 molecule, called Thy-1.1 and Thy-1.2. Engrafting Thy-1.1 thymic lobes in Thy-1.2 mice resulted in the presence of Thy-1.1 dEC in the skin, demonstrating that the dEC derived from the engrafted thymus rather than the host bone marrow, which has Thy-1.2. Apparently, although later migrations of cells from the bone marrow may take up residence in the skin as dendritic epidermal cells, only cells that have had access to the thymus in early life are capable of developing the full repertoire of antigens. (Consumer Summary produced by Reliance Medical Information, Inc.)

Epidermis, Immunocompetent cells, Immunocompetence

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Thymic dendritic cells and T cells develop simultaneously in the thymus from a common precursor population

Article Abstract:

An investigation of the origin of thymic dendritic cells is reported. Thymic dendritic cells comprise a minor cell population in lymphoid tissues which are specialized for presenting antigenic peptides to T lymphocytes. All thymic dendritic cells ultimately come from the bone marrow, but it is not clear whether they migrate to the thymus as cell precursors or as preformed dendritic cells from the periphery. The study protocol involved the isolation from adult mouse thymus of thymic lymphoid precursor cells. These cells form dendritic and T cell progeny when transferred to an irradiated thymus, indicating a linked origin for T-cells and dendritic cells.

Research, Stem cells, Immune system

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A cell line that can induce thymocyte positive selection

Article Abstract:

Thymocytes which recognize antigens presented by the body's major histocompatibility complex (MHC) proteins are positively selected in the thymus. H-2b-expressing thymic epithelial cells were introduced into the thymuses of irradiated H-2k mice. The presence of I-Ab-restricted T cells in these animals shows that selection for the cells occurred on the introduced epithelial cells. Since the introduced epithelial cell lines are easily manipulated, they should prove useful to study the molecules involved in the selection mechanism.

Immune response

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