title: Thymus-independent positive and negative selection of T cells expressing a major histocompatibility complex class I restricted transgenic T cell receptor alpha/beta in the intestinal epithelium.
abstract: We demonstrate that in the mouse intestinal epithelium the selection of T lymphocytes expressing a transgenic T cell receptor alpha/beta (TCR-alpha/beta) specific for male antigen (H-Y) in the context of H-2Db depends on the differential expression of H-Y and H-2Db in situ. In H-2Db transgenic males, there is no reduction in the number of intestinal intraepithelial lymphocytes (IEL), and the four main subsets of IEL expressing TCR-alpha/beta, defined by the differential expression of CD4, CD8 alpha, and CD8 beta, are present. Moreover, the level of expression of CD8 alpha and CD8 beta on CD8+ IEL subsets is unaltered. The frequency of CD8 alpha+ IEL expressing CD8 beta, in H-2Db male mice, however, is significantly decreased and these cells do not express the transgenic TCR. In contrast, virtually all CD8 alpha+beta- IEL in the same animals express the transgenic TCR. Still, these potentially autoreactive cells are refractile to H-Y/H-2Db stimulation in vitro. Both H-2Db and H-2Dd transgenic females contain high frequencies of cells expressing the transgenic TCR among CD8 alpha+beta- and CD8 alpha+beta+ IEL. However, two possibly related phenotypic features are peculiar to H-2Db female mice. The frequency of CD8 alpha+ IEL expressing CD8 beta is increased in these mice and, while in H-2Dd females the level of the transgenic TCR alpha chain expressed on CD8 alpha+beta+ IEL is uniformly low, some of the CD8 alpha+beta+ IEL in H-2Db females express a high level of both transgenic TCR chains. It is important to note, the ability of CD8 alpha+beta+ IEL to respond to H-Y/H-2Db stimulation in vitro is restricted to those coexpressing a high level of both transgenic TCR chains. The analysis of athymic radiation chimeras using adult thymectomized recipients of distinct H-Y/H-2 haplotypes, reconstituted with bone marrow from H-2Db transgenic females, demonstrates that all IEL subsets present in unmanipulated transgenic animals develop in the absence of a thymus. These IEL are phenotypically identical to those found in unmanipulated transgenic animals sharing the H-Y/H-2 haplotype of athymic recipients. Taken together, these results demonstrate that in the absence of male antigen, expression of H-2Db in the intestinal epithelium results in the positive selection of functional IEL specific for male antigen, in situ. When both H-Y and H-2Db are expressed in the intestinal epithelium, CD8 alpha+beta+ IEL expressing the transgenic TCR are negatively selected, while the frequency of nonfunctional CD8 alpha+beta- IEL expressing the transgenic CR is increased.(ABSTRACT TRUNCATED AT 400 WORDS)
authors.affiliation: Department of Medicine, McGill University, Montreal, Quebec, Canada.
authors.forename: P
authors.initials: P
authors.lastname: Poussier
authors.forename: H S
authors.initials: HS
authors.lastname: Teh
authors.forename: M
authors.initials: M
authors.lastname: Julius
mesh_terms: D000818:Animals; D016827:CD8 Antigens / Q000378:metabolism; D005260:Female; D006183:H-2 Antigens / Q000276:immunology; D006182:H-Y Antigen / Q000276:immunology; D007413:Intestinal Mucosa / Q000276:immunology*; D008213:Lymphocyte Activation; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000378:metabolism*; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D013950:Thymus Gland / Q000276:immunology*
chemical_list: D016827:CD8 Antigens; D006183:H-2 Antigens; D006182:H-Y Antigen; D016693:Receptors, Antigen, T-Cell, alpha-beta