title: Costimulatory function of CD28 in avian gammadelta T cells is evolutionarily conserved.
abstract: CD28 costimulatory signals are required for T-cell proliferation and lymphokine production. In this work, the functional conservation of CD28 was studied in avian gammadelta T cells. The avian CD28 molecule is expressed on all alphabeta T cells and is capable of giving a costimulatory signal. Most peripheral gammadelta T cells are CD28 negative; however, we identified a CD28-positive gammadelta T-cell subset from peripheral blood comprising about 12% of gammadelta T cells. The peripheral CD28+ gammadelta T-cell subset included all CD8+ gammadelta T cells known to be a responding subset during activation. After polyclonal activation, the frequency of CD28+ gammadelta T cells was increased and the activation also up-regulated CD5, CD25 and major histocompatibility complex (MHC) class II molecules. These changes were detected after both polyclonal and antigen-specific T-cell activation. In addition, we also showed that CD28 can give a costimulatory signal to gammadelta T cells and that this signal leads to up-regulation of IL-2 and bcl-x transcripts. These results indicate that the function of CD28 is evolutionarily conserved and can already be detected in avian gammadelta T cells.
authors.affiliation: Turku Immunology Centre and Department of Medical Microbiology, Turku University, Finland.
authors.forename: K
authors.initials: K
authors.lastname: Koskela
authors.forename: T P
authors.initials: TP
authors.lastname: Arstila
authors.forename: O
authors.initials: O
authors.lastname: Lassila
mesh_terms: D000818:Animals; D005075:Biological Evolution; D018106:CD28 Antigens / Q000378:metabolism*; D018956:CD5 Antigens / Q000378:metabolism; D002478:Cells, Cultured; D002645:Chickens; D000949:Histocompatibility Antigens Class II / Q000378:metabolism; D007376:Interleukin-2 / Q000096:biosynthesis; D008213:Lymphocyte Activation; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000378:metabolism*; D015375:Receptors, Interleukin-2 / Q000378:metabolism; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000378:metabolism*; D015854:Up-Regulation; D051020:bcl-X Protein
chemical_list: D018106:CD28 Antigens; D018956:CD5 Antigens; D000949:Histocompatibility Antigens Class II; C041136:Ia-like antigens, avian; D007376:Interleukin-2; D019253:Proto-Oncogene Proteins c-bcl-2; D016692:Receptors, Antigen, T-Cell, gamma-delta; D015375:Receptors, Interleukin-2; D051020:bcl-X Protein