T-CELL DIFFERENTIATION IS INFLUENCED BY THYMIC MICROENVIRONMENTS

Intrathymic T-cell differentiation requires a symbiotic interaction between thymic microenvironments and developing T cells. This paper attempts to provide insight into lympho-stromal interaction and reviews the architecture of thymic microenvironments, the phenotype of thymic micro-environments, the in vitro culture of thymic microenvironments, and the supportive role of thymic microenvironments in T-cell differentiation. Moreover, we discuss experimental manipulation of thymic microenvironments in vivo and in vitro, using monoclonal antibodies directed to cell surface determinants on stromal cells or their ligands on lymphoid cells. Finally, new types of experimental mouse models are considered with special reference to the role of thymic microenvironments in positive and negative selection of the T-cell repertoire, and the potential influence of T cells on the development of thymic microenvironments.