title: Regeneration and tolerance factor's potential role in T-cell activation and apoptosis.
abstract: Regeneration and tolerance factor (RTF) is a novel membrane protein that has a diverse expression pattern and immunoregulatory properties. RTF is expressed in vivo on the surface of individuals with B cell chronic lymphocytic leukemia and on activated T lymphocytes of HIV infected individuals as determined by their coexpression with CD38 and HLA-DR. The unique expression patterns of this protein in vivo lead us to investigate its expression in vitro. The activation of human PBMCs through the TCR, using anti-CD3 antibody and PMA, upregulated cell surface expression of RTF from 2. 3% to 91.2% (mean channel fluorescence [MCF] increased threefold). The activation of Jurkat T cells through the TCR upregulated surface expression of RTF from 8.3% (MCF-1.3) to 58.7% (MCF-13.1). The Jurkat T-cell line was used as a model system to explore RTF's role in cellular activation. Using the Jurkat T-cell model, we found anti-RTF antibody induces apoptosis. The addition of anti-RTF antibody increased annexin V binding by threefold compared with the IgG1 kappa isotype control antibody (p < 0.00002) and activated caspase 3. These data indicate that RTF is expressed during T-cell activation and may be associated with apoptosis.
authors.affiliation: Clinical Immunology Laboratory, Department of Microbiology/Immunology, Finch University of Health Sciences/The Chicago Medical School, North Chicago, Illinois 60064, USA.
authors.forename: J S
authors.initials: JS
authors.lastname: Boomer
authors.forename: G W
authors.initials: GW
authors.lastname: Lee
authors.forename: T S
authors.initials: TS
authors.lastname: Givens
authors.forename: A
authors.initials: A
authors.lastname: Gilman-Sachs
authors.forename: K D
authors.initials: KD
authors.lastname: Beaman
mesh_terms: D000906:Antibodies / Q000276:immunology; D017209:Apoptosis; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D004789:Enzyme Activation; D006801:Humans; D019169:Jurkat Cells; D007963:Leukocytes, Mononuclear / Q000276:immunology; D008213:Lymphocyte Activation; D011257:Pregnancy Proteins / Q000276:immunology / Q000378:metabolism*; D013491:Suppressor Factors, Immunologic / Q000276:immunology / Q000378:metabolism*; D013601:T-Lymphocytes / Q000276:immunology*; D006180:Proton-Translocating ATPases
chemical_list: D000906:Antibodies; D053148:Caspase 3; D020169:Caspases; D011257:Pregnancy Proteins; D013491:Suppressor Factors, Immunologic; C505407:CASP3 protein, human; C525845:ATP6V0A2 protein, human; D006180:Proton-Translocating ATPases