title: CD5 (OKT1) augments CD3-mediated intracellular signaling events in human T lymphocytes.
abstract: CD5 is expressed on thymocytes, all mature T cells, and a subset of mature B cells, and probably contributes to T-cell-B-cell adhesion. We assessed whether CD5-crosslinking by mAb augments T-cell stimulation. Plate-bound anti-CD5 or anti-CD3 mAb alone had no effect on any of the assessed activation parameters of resting T cells. However, concomitant signaling through both CD5 and CD3 by plate-bound antibodies resulted in marked increases in T-cell surface CD69 expression and T-cell metabolism, as assessed by the T cell's ability to reduce 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxylmethoxyphenyl)-2-(4-sulphophenyl)-2H-tetrazolium (MTS) to formazen. In addition, simultaneous cross-linking of CD5 and CD3 caused a significant (p < 0.001) increase in phosphatidylinositol hydrolysis in resting T cells compared to stimulation with anti-CD3 mAb alone or anti-CD3 mAb plus anti-CD5 isotype control antibody. These results indicate that CD5 augments signaling through CD3 and consequently functions as a costimulatory molecule for resting T cells.
authors.affiliation: Department of Medicine-Section of Rheumatology/Center of Excellence for Arthritis and Rheumatology, Shreveport, Louisiana 71130-3932, USA. sberne@lsumc.edu
authors.forename: S M
authors.initials: SM
authors.lastname: Berney
authors.forename: T
authors.initials: T
authors.lastname: Schaan
authors.forename: R E
authors.initials: RE
authors.lastname: Wolf
authors.forename: D L
authors.initials: DL
authors.lastname: Kimpel
authors.forename: H
authors.initials: H
authors.lastname: van der Heyde
authors.forename: T P
authors.initials: TP
authors.lastname: Atkinson
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D015703:Antigens, CD / Q000096:biosynthesis; D000945:Antigens, Differentiation, T-Lymphocyte / Q000096:biosynthesis; D017252:CD3 Complex / Q000276:immunology / Q000502:physiology*; D018956:CD5 Antigens / Q000276:immunology / Q000502:physiology*; D006801:Humans; D006868:Hydrolysis; D037181:Lectins, C-Type; D008875:Middle Aged; D010716:Phosphatidylinositols / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D000099192:CD69 Antigens
chemical_list: D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D017252:CD3 Complex; D018956:CD5 Antigens; D037181:Lectins, C-Type; D010716:Phosphatidylinositols; D000099192:CD69 Antigens