title: The expression of CD8α discriminates distinct T cell subsets in teleost fish.
abstract: CD8, belonging to the TCR complex, is the main marker molecule of CTLs. Although CD8 genes have been detected in many fish species, the analysis of teleost CD8+ cells has been limited because of the lack of antibodies. Using newly established mAbs against rainbow trout CD8α, we found high ratios of CD8α+ cells in trout thymus, gill and intestine, but relatively low abundance in pronephros, spleen and blood. Accordingly, tissue sections revealed many CD8α+ cells in thymus, numerous intra- and subepithelial CD8α+ cells in intestine and gill and few scattered CD8α+ cells in spleen and pronephros. In secondary lymphoid tissues, CD8α+ lymphocytes, which did not react with anti-thrombocyte or anti-IgM mAbs, expressed CD8α, CD8β and TCRα, while Ig and CD4 transcripts were found in CD8α⁻ lymphocytes. In contrast, considerable CD4 expression in CD8α+ thymocytes suggests the presence of double-positive early T cells. Highly expressed TCRγ, LAG3 and CTLA4 in CD8α+ lymphocytes imply that they constitute a heterogeneous population different from found in non-mucosal tissues. PHA stimulation resulted in an up-regulation of CTL effector genes (perforin, granulysin and IFN-γ) in CD8α+ pronephrocytes, while both Th1 (IFN-γ) and Th2 (IL-4/13A) cytokines were up-regulated in CD8α⁻ pronephrocytes. Although the basic characteristics of CD8α+ lymphocytes seem similar in teleost and mammals, features such as the low proportion of teleost CD8α+ lymphocytes in blood and their high abundance in respiratory tissue reveal a unique dynamics and distribution.
authors.affiliation: Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Institute of Infectology, 17493 Greifswald-Insel Riems, Germany.
authors.forename: Fumio
authors.initials: F
authors.lastname: Takizawa
authors.forename: Johannes Martinus
authors.initials: JM
authors.lastname: Dijkstra
authors.forename: Paul
authors.initials: P
authors.lastname: Kotterba
authors.forename: Tomáš
authors.initials: T
authors.lastname: Korytář
authors.forename: Holger
authors.initials: H
authors.lastname: Kock
authors.forename: Bernd
authors.initials: B
authors.lastname: Köllner
authors.forename: Beltran
authors.initials: B
authors.lastname: Jaureguiberry
authors.forename: Teruyuki
authors.initials: T
authors.lastname: Nakanishi
authors.forename: Uwe
authors.initials: U
authors.lastname: Fischer
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000302:isolation & purification / Q000378:metabolism; D015703:Antigens, CD / Q000235:genetics / Q000378:metabolism; D016827:CD8 Antigens / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D060908:CTLA-4 Antigen; D002465:Cell Movement / Q000235:genetics; D016207:Cytokines / Q000235:genetics / Q000378:metabolism; D020869:Gene Expression Profiling; D018928:Immunity, Mucosal / Q000235:genetics; D054503:Lymphoid Progenitor Cells / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D008322:Mammals; D017686:Oncorhynchus mykiss; D009928:Organ Specificity; D016176:T-Lymphocyte Subsets / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D000093322:Lymphocyte Activation Gene 3 Protein
chemical_list: D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D016827:CD8 Antigens; C409469:CD8 antigen, alpha chain; D060908:CTLA-4 Antigen; D016207:Cytokines; D000093322:Lymphocyte Activation Gene 3 Protein