title: Generation of alphabeta T-cell receptor+ CD4- CD8+ cells in major histocompatibility complex class I-deficient mice upon activation of the aryl hydrocarbon receptor by 2,3,7,8-tetrachlorodibenzo-p-dioxin.
abstract: Gene-targeted mice lacking the beta2 microglobulin gene (beta2m-/- mice), and hence functional major histocompatibility complex (MHC) class I molecules, do not develop CD4- CD8+ cells. We show here that both in vitro and in vivo treatment with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a trans-activating ligand of the endogenous aryl hydrocarbon receptor (Ah-R), bypasses the need for MHC class I molecules for selection into the CD4- CD8+ cell pool. When beta2m-/- dams were given a single dose of 50 microg of TCDD, approximately 13% of CD4- CD8+ thymocytes could be detected in their newborn pups. In TCDD-exposed fetal thymus organ cultures of beta2m-/- mice, approximately 35% CD4- CD8+ thymocytes were detectable. About 16% of these CD4- CD8+ cells bore the alpha beta T-cell receptor (TCR) and approximately 33% bore CD3. Only a minority of the CD8+ cells were heat-shock antigen positive. The cells possessed killing activity as shown using the 51Cr-release assay comprising gamma delta TCR- CD4- CD8+ thymocytes from 3 to 4-day-old b2m-/- mice. Thus, TCDD leads to a significant increase of mature CD4- CD8+ thymocytes in relative and absolute numbers. High numbers of CD4- CD8+ thymocytes developed also in organ cultures from thymi, lacking both MHC class I and class II molecules, exposed to TCDD. A 10-fold transient increase of Notch1 mRNA in thymocytes from fetal thymus organ culture, exposed for 4 days to TCDD, was detected in CD4+ CD8+ cells compared with controls. We suggest that TCDD affects thymic selection and directs the lineage commitment of CD4+ CD8+ thymocytes towards CD4- CD8+ cells, possibly via up-regulation of the Notch1 gene.
authors.affiliation: Division of Immunology, Medical Institute of Environmental Hygiene at Heinrich-Heine-University of D]usseldorf, D]usseldorf, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Kronenberg
authors.forename: Z
authors.initials: Z
authors.lastname: Lai
authors.forename: C
authors.initials: C
authors.lastname: Esser
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D017252:CD3 Complex / Q000032:analysis; D015704:CD4 Antigens / Q000032:analysis; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D003602:Cytotoxicity, Immunologic; D004785:Environmental Pollutants / Q000494:pharmacology*; D005260:Female; D015395:Histocompatibility Antigens Class I / Q000276:immunology*; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D000072317:Polychlorinated Dibenzodioxins / Q000494:pharmacology*; D011247:Pregnancy; D051881:Receptor, Notch1; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000032:analysis*; D018336:Receptors, Aryl Hydrocarbon / Q000187:drug effects / Q000378:metabolism*; D011956:Receptors, Cell Surface; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013950:Thymus Gland / Q000187:drug effects / Q000196:embryology / Q000276:immunology; D014157:Transcription Factors; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D017252:CD3 Complex; D015704:CD4 Antigens; D004785:Environmental Pollutants; D015395:Histocompatibility Antigens Class I; D008565:Membrane Proteins; C497762:Notch1 protein, mouse; D000072317:Polychlorinated Dibenzodioxins; D051881:Receptor, Notch1; D016693:Receptors, Antigen, T-Cell, alpha-beta; D018336:Receptors, Aryl Hydrocarbon; D011956:Receptors, Cell Surface; D014157:Transcription Factors