Effect of cytokines on thymic hematopoietic precursors |
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Authors: | Bernadette Nabarra Martine Papiernik |
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Institution: | (1) INSERM U 25, CNRS UA 122, Hôpital Necker, 161, Rue de Sèvres, F-75743 Paris Cedex 15, France |
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Abstract: | Summary We have previously shown that the interaction of thymocytes with thymic accessory cells (macrophages and/or interdigitating cells) is one of the factors required for thymocyte activation. Precursors of both thymic accessory cell and thymocytes are included in the CD4- CD8- Mac-1- Ia- subpopulation, and their respective maturation and/or activation may be modulated by granulocyte-macrophage colony-stimulating factor, interleukin 1 and interleukin 2. When CD4- CD8- thymic cells are activated with granulocyte-macrophage colony-stimulating factor plus interleukin 2, both macrophages and interdigitating-like cells are present, as shown by electron microscopy. When activated with interleukin 1 plus interleukin 2, the interdigitating-like cells is the only accessory cell present. In both culture conditions, large clusters are formed between interdigitating cells and lymphoid cells. These results have led us to propose two-step signals for thymocyte proliferation: first, the maturation of macrophages under granulocyte-macrophage colony-stimulating factor control and the production of interleukin 1, and secondly, the maturation of interdigitating cells under interleukin 1 control, their clustering with thymocytes which are then activated.Abbreviations CFU-S
colony-forming units in the spleen
- CSF
colony-stimulating factor
- DC
dendritic cells
- DN
double negative cells (CD4- CD8-)
- EC
epithelial cells
- GM-CFC
granulocyte/macrophage colony-forming cells
- GM-CSF
granulocytemacrophage CSF
- IDC
interdigitating cell
- IL-1
interleukin 1
- IL-2
interleukin 2
- MØ
macrophage
- P-TR
phagocytic cell of the thymic reticulum |
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Keywords: | Thymus CD4- CD8- thymocyte Thymic hematopoietic precursors Cytokines Ultrastructure Mouse (DBA/2 H-2d) |
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