T lymphocytes, the effectors of cell-mediated immunity, are concerned with the control of intracellular infections: cytotoxic T lymphocytes recognize and destroy vi rally infected cells, whereas helper T lymphocytes, through lymphokines, may activate macrophages in killing intracellular parasites. The parasitaljviral antigens are recognized by the T lymphocytes in association with molecules of the major histocompatibility complex (MHC). This ability, to recognize antigens in the context of self-MHC molecules, also termed MHC-restriction, is learned by the T lymphocytes during their development in the thymus. On their pathway to development (maturation), T cells are differentially influenced by various thymic stromal cells. The stromal cells constitute microenvironments, where developing T cells, through cell-cell interactions and locally secreted cytokines, receive signals to proliferate and mature. This thesis focuses on the specific role of thymic microenvironments in promoting sequential stages in T cell development in the murine thymus. Our understanding of these lymphostromal interactions will be introduced in this chapter, containing three major sections. The first section on "Development and architecture of thymic microenvironments" discusses the variety of thymic microenvironments that have presently been identified. The phenotypic characterization of thymic microenvironments, presented in this section, is more extensively reviewed in chapter 2. The second section on ''T cell differentiation" introduces a major pathway of T cell differentiation, including the a/3 and the yo T cell lineages, showing the complexity of this process. The third section on "Lymphostromal interactions" links the different types of stromal cells to distinct stages ofT cell development. The chapter ends with an "Introduction to the experimental work".

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W. van Ewijk (Willem)
Erasmus University Rotterdam
Erasmus MC: University Medical Center Rotterdam

Brekelmans, P.J.A.M. (1993, December 8). T cell development in mouse thymus : studies on lymphostromal interactions . Erasmus University Rotterdam. Retrieved from http://hdl.handle.net/1765/37809