title: Phenotypic analysis of peripheral CD4+ CD8+ T cells in the rat.
abstract: Among peripheral T cells, the expression of CD4 and CD8 is almost mutually exclusive. However, here we show, using flow cytometric analysis, that ex vivo approximately 6% of rat T cells stained for both CD4 and CD8. These double positive cells were also detected by confocal microscopy. Only around 50% of double positive cells expressed the CD8beta chain, the remaining cells expressed the CD8alpha chain alone. Double positive cells were blast-like with a phenotype, distinct from that of either CD4 or CD8 single positive cells, suggestive of an activated state. Previous reports of double positive T cells have also suggested that coexpression of CD4 and CD8 is linked to the activation state of the cell. There was an indication that priming animals with a hapten-carrier complex increased the ratio of CD8alphaalpha : alphabeta expressing double positive T cells, although we did not detect an increase in the frequency of double positive T cells following priming. We also show that the frequency of double positive cells was reduced following thymectomy and with age. In conclusion, these studies show that peripheral T cells expressing both CD4 and CD8 can be detected in the rat and that they are phenotypically distinct from CD4 and CD8 single positive T cells.
authors.affiliation: Sir William Dunn School of Pathology, University of Oxford, Oxford, UK.
authors.forename: E
authors.initials: E
authors.lastname: Kenny
authors.forename: D
authors.initials: D
authors.lastname: Mason
authors.forename: A
authors.initials: A
authors.lastname: Pombo
authors.forename: F
authors.initials: F
authors.lastname: Ramírez
mesh_terms: D000375:Aging / Q000276:immunology; D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D016130:Immunophenotyping; D008213:Lymphocyte Activation / Q000276:immunology; D018613:Microscopy, Confocal; D051381:Rats; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000032:analysis; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D013950:Thymus Gland / Q000276:immunology
chemical_list: D016693:Receptors, Antigen, T-Cell, alpha-beta