title: Rescue of cytotoxic function in the CD8alpha knockout mouse by removal of MHC class II.
abstract: CD8 plays an important role in the activity of cytolytic T cells (CTL). However, whether or not CD8 is required for the development of CTL has not been clearly determined. Cytotoxic activity in the CD8alpha knockout mouse is difficult to induce, and has only been demonstrated against allogenic MHC targets. The lack of cytotoxicity may result from impaired lineage commitment of CTL in the absence of CD8, or diminished competitiveness during selection against (unimpaired) development of CD4(+) T cells on MHC class II (MHC II). To differentiate between these possibilities, we have generated a double-knockout mouse (MHC II(-/-)CD8alpha(-/-)). In MHC II(-/-)CD8alpha(-/-) mice, developing MHC class I (MHC I)-reactive thymocytes cannot rely upon CD8 for selection, but they also cannot be overwhelmed by efficient selection of MHC II-reactive thymocytes. In this mouse, a large, heterogeneous population of peripheral coreceptor double-negative (DN) and CD4(+) T cells develops. Peripheral DN T cells are fully functional CTL. They display cytolytic activity against allogeneic MHC, and against syngeneic MHC following lymphocytic choriomeningitis virus (LCMV) infection. Cells from LCMV-infected mice bind more MHC I tetramer at lower concentrations than their wild-type CTL counterparts. These results demonstrate unequivocally that CD8 is not required for commitment of thymocytes to the CTL lineage.
authors.affiliation: University of North Carolina at Chapel Hill, Department of Microbiology and Immunology, Chapel Hill, NC 27599-7290, USA.
authors.forename: David S
authors.initials: DS
authors.lastname: Riddle
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Miller
authors.forename: Benjamin G
authors.initials: BG
authors.lastname: Vincent
authors.forename: Thomas B
authors.initials: TB
authors.lastname: Kepler
authors.forename: Rob
authors.initials: R
authors.lastname: Maile
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Frelinger
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Collins
mesh_terms: D000818:Animals; D000956:Antigens, Viral / Q000276:immunology / Q000378:metabolism; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology; D016827:CD8 Antigens / Q000235:genetics / Q000276:immunology*; D002452:Cell Count; D022801:Complementarity Determining Regions / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D018984:Epitopes, T-Lymphocyte / Q000276:immunology / Q000378:metabolism; D006023:Glycoproteins / Q000276:immunology / Q000378:metabolism; D006085:Graft Survival / Q000276:immunology; D000949:Histocompatibility Antigens Class II / Q000235:genetics / Q000276:immunology*; D007959:Lymphocyte Culture Test, Mixed; D008216:Lymphocytic Choriomeningitis / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008815:Mice, Inbred Strains; D018345:Mice, Knockout; D010446:Peptide Fragments / Q000276:immunology / Q000378:metabolism; D011485:Protein Binding / Q000276:immunology; D011948:Receptors, Antigen, T-Cell / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D016038:Skin Transplantation / Q000276:immunology / Q000379:methods; D013154:Spleen / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D016176:T-Lymphocyte Subsets / Q000166:cytology / Q000276:immunology; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology* / Q000378:metabolism; D013950:Thymus Gland / Q000033:anatomy & histology / Q000166:cytology / Q000276:immunology; D014184:Transplantation, Homologous; D014764:Viral Proteins / Q000276:immunology / Q000378:metabolism
chemical_list: D000956:Antigens, Viral; D016827:CD8 Antigens; C409469:CD8 antigen, alpha chain; D022801:Complementarity Determining Regions; D018984:Epitopes, T-Lymphocyte; D006023:Glycoproteins; D000949:Histocompatibility Antigens Class II; D010446:Peptide Fragments; D011948:Receptors, Antigen, T-Cell; D016693:Receptors, Antigen, T-Cell, alpha-beta; D014764:Viral Proteins; C094244:glycoprotein peptide 33-41, Lymphocytic choriomeningitis virus