title: CD4+CD8- thymocytes that express L-selectin protect rats from diabetes upon adoptive transfer.
abstract: Previous studies have shown that insulin-dependent diabetes can be induced in normal PVG.RT1u rats by a protocol of adult thymectomy and irradiation. The injection of CD4+ T cells from non-irradiated syngeneic donors prevents the onset of disease in approximately 50% of pre-diabetic recipients but all rats are protected if a particular subset of CD4+ cells is transferred. These protective cells express TCR alpha beta and have a memory phenotype, being CD45RClow RT6+. Further studies have demonstrated that the transfer of CD4+CD8- thymocytes, like that of unfractionated CD4+ peripheral T cells, also protects approximately half of recipients from diabetes suggesting that, as with the peripheral T cells, a functional heterogeneity may exist amongst CD4+CD8- thymocytes. In this study, we show that L-selectin is expressed by 50-60% of all CD4+CD8- thymocytes from 6-week-old rats. Adoptive transfer of these populations into thymectomized and irradiated rats revealed that the protection from diabetes observed by CD4+CD8- thymocytes was mediated almost entirely by the L-selectin+ subset. Cells with this phenotype were also able to mediate both humoral and cell mediated responses, providing primed B cells with help for secondary antibody responses and mediating local graft-versus-host reactions. L-selectin- CD4+CD8- thymocytes failed to mediate these responses. These data indicate that CD4+CD8- thymocytes must mature to the stage of L-selectin expression, before they can mediate normal T cell function. The implications of these results are discussed with respect to the possible role of murine NK1.1+ thymocytes in the control of autoimmunity.
authors.affiliation: MRC Cellular Immunology Unit, Sir William Dunn School of Pathology, University of Oxford, GB.
authors.forename: B
authors.initials: B
authors.lastname: Seddon
authors.forename: A
authors.initials: A
authors.lastname: Saoudi
authors.forename: M
authors.initials: M
authors.lastname: Nicholson
authors.forename: D
authors.initials: D
authors.lastname: Mason
mesh_terms: D019264:Adoptive Transfer; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D015704:CD4 Antigens / Q000032:analysis*; D016827:CD8 Antigens / Q000032:analysis*; D016207:Cytokines / Q000096:biosynthesis; D003922:Diabetes Mellitus, Type 1 / Q000276:immunology*; D006087:Graft vs Host Reaction / Q000276:immunology; D019041:L-Selectin / Q000096:biosynthesis*; D051381:Rats; D011919:Rats, Inbred Strains; D016176:T-Lymphocyte Subsets / Q000276:immunology / Q000378:metabolism* / Q000637:transplantation*; D018417:Th1 Cells / Q000378:metabolism; D013950:Thymus Gland / Q000166:cytology* / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D015704:CD4 Antigens; D016827:CD8 Antigens; D016207:Cytokines; D019041:L-Selectin