Effect of cytokines on thymic hematopoietic precursors. Phenotypic and electron-microscopic study.
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 cells 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 cell 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.
Nabarra
B
B
INSERM U 25, CNRS UA 122, Hôpital Necker, Paris, France.
Papiernik
M
M
D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology / Q000648:ultrastructure; D016207:Cytokines / Q000494:pharmacology*; D005260:Female; D006412:Hematopoietic Stem Cells / Q000276:immunology* / Q000648:ultrastructure; D066298:In Vitro Techniques; D051379:Mice; D008811:Mice, Inbred DBA; D008854:Microscopy, Electron; D010641:Phenotype; D013601:T-Lymphocytes / Q000276:immunology / Q000648:ultrastructure; D013950:Thymus Gland / Q000276:immunology* / Q000648:ultrastructure
D016207:Cytokines