Thymic and extrathymic T cell development.
The majority of T cells located in peripheral blood, spleen and lymph nodes are dependent on the thymus for proper differentiation and function. Only a minority of T lymphocytes located in these lymphoid organs is thymic-independent. In contrast, a large number of thymus-independent T cells is present in the gut epithelium. This review deals with phenotypic and functional characteristics of T cell development, summarizes the knowledge on the cytokine requirement in this process and describes positive and negative selection. The differences between thymic-dependent and thymic-independent T cells are emphasized, including selection processes, CD4-CD8 expression and the composition of the CD3 complex.
Leclercq
G
G
Department of Clinical Chemistry, Microbiology and Immunology, University of Ghent, Belgium.
Plum
J
J
D000818:Animals; D006801:Humans; D013601:T-Lymphocytes / Q000166:cytology*; D013950:Thymus Gland / Q000166:cytology*