title: Selection of peripheral and intestinal T lymphocytes lacking CD3 zeta.
abstract: The CD3 zeta chain of the TCR plays a pivotal role in the activation of T cell responses toward foreign antigen and in the selection of the T cell repertoire. T lymphocytes from mice deficient in CD3 zeta (CD3 zeta/eta-/- mice) express very few cell surface TCR-CD3 complexes, and these animals have poorly developed thymuses which lack single-positive CD8 and CD4 thymocytes. Nevertheless, a substantial number of single-positive CD4+ and CD8+ T lymphocytes are found in peripheral lymphoid organs of CD3 zeta/eta-/- animals. Using double-mutant mice, generated by breeding CD3 zeta/eta-/- mice with others deficient in the expression of either class I or class II MHC molecules, we demonstrate here that positive selection of peripheral CD4+ and CD8+ T lymphocytes can occur in the absence of CD3 zeta/eta molecules. Analysis of the intestinal intra-epithelial lymphocytes from CD3 zeta/eta-/- mice revealed a novel T cell population expressing high levels of an alternative TCR alpha beta, due to the replacement of CD3 zeta by Fc epsilon RI gamma. Developmentally, these cells also depend on class I MHC expression. In contrast, TCR gamma delta/Fc epsilon RI gamma+ T cells develop independently of MHC class I or class II molecules. These experiments demonstrate that the unique subset of intestinal TCR alpha beta/Fc epsilon RI gamma+ lymphocytes is developmentally dependent on MHC expression. The restricted expression of TCR alpha beta/Fc epsilon RI gamma+ cells in the intestinal mucosa (rather than the thymus or lymph nodes) supports the hypothesis that selection of these T cells occurs extrathymically.
authors.affiliation: Department of Medicine, Beth Israel Hospital, Harvard Medical School, Boston, MA 02215, USA.
authors.forename: S
authors.initials: S
authors.lastname: Simpson
authors.forename: G
authors.initials: G
authors.lastname: Holländer
authors.forename: J
authors.initials: J
authors.lastname: She
authors.forename: C
authors.initials: C
authors.lastname: Levelt
authors.forename: M
authors.initials: M
authors.lastname: Huang
authors.forename: C
authors.initials: C
authors.lastname: Terhorst
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D005434:Flow Cytometry; D015395:Histocompatibility Antigens Class I / Q000235:genetics; D000949:Histocompatibility Antigens Class II / Q000235:genetics; D007413:Intestinal Mucosa / Q000276:immunology*; D008565:Membrane Proteins / Q000235:genetics* / Q000276:immunology*; D051379:Mice; D008817:Mice, Mutant Strains; D017260:Receptor-CD3 Complex, Antigen, T-Cell / Q000235:genetics* / Q000276:immunology*; D011948:Receptors, Antigen, T-Cell / Q000235:genetics* / Q000276:immunology*; D017455:Receptors, IgE / Q000276:immunology; D016176:T-Lymphocyte Subsets / Q000276:immunology*
chemical_list: D015395:Histocompatibility Antigens Class I; D000949:Histocompatibility Antigens Class II; D008565:Membrane Proteins; D017260:Receptor-CD3 Complex, Antigen, T-Cell; D011948:Receptors, Antigen, T-Cell; D017455:Receptors, IgE; C054979:antigen T cell receptor, zeta chain