title: Tumor necrosis factor-alpha regulates the expression of inducible costimulator receptor ligand on CD34(+) progenitor cells during differentiation into antigen presenting cells.
abstract: The inducible costimulator receptor (ICOS) is a third member of the CD28 receptor family that regulates T cell activation and function. ICOS binds to a newly identified ligand on antigen presenting cells different from the CD152 ligands CD80 and CD86. We used soluble ICOSIg and a newly developed murine anti-human ICOS ligand (ICOSL) monoclonal antibody to further characterize the ICOSL during ontogeny of antigen presenting cells. In a previous study, we found that ICOSL is expressed on monocytes, dendritic cells, and B cells. To define when ICOSL is first expressed on myeloid antigen presenting cells, we examined ICOSL expression on CD34(+) cells in bone marrow. We found that CD34(bright) cells regardless of their myeloid commitment were ICOSL(-), whereas ICOSL was first expressed when CD34 expression diminished and the myeloid marker CD33 appeared. However, acute myeloid leukemia cells were ICOSL-negative, whereas among B-cell malignancies only some cases of the most mature tumors such as prolymphocytic leukemia and hairy cell leukemia were positive. Next, we investigated purified CD34(+) hematopoietic progenitor cells that did not constitutively express ICOSL but were induced to express ICOSL within 12 h after granulocyte/macrophage colony-stimulating factor/tumor necrosis factor alpha (TNF-alpha) stimulation. Interestingly, ICOSL was induced prior to CD80/CD86 induction on CD34(+) cells so that ICOSL was expressed in the absence of CD80/CD86. This suggests that ICOSL is an early differentiation marker along the monocytic/dendritic maturation pathway. Induction of ICOSL was dependent on TNF-alpha and was regulated via NF-kappa B as revealed by use of inhibitors specific for I kappa B alpha phosphorylation such as BAY 11-7082 and BAY 11-7085. The antigen presenting capacity of TNF-alpha stimulated CD34(+) cells was strongly inhibited by ICOSIg fusion proteins or by NF-kappa B inhibition. Thus, TNF-alpha-induced ICOSL expression seemed to be functionally important for the costimulatory capacity of CD34(+) hematopoietic progenitor cells.
authors.affiliation: Department of Hematology, Oncology and Tumor Immunology, Robert-Rössle-Klinik, Charité, Humboldt University, Lindenberger Weg 80, 13125 Berlin, Germany. guenther.richter@medizin.uni-halle.de
authors.forename: G
authors.initials: G
authors.lastname: Richter
authors.forename: M
authors.initials: M
authors.lastname: Hayden-Ledbetter
authors.forename: M
authors.initials: M
authors.lastname: Irgang
authors.forename: J A
authors.initials: JA
authors.lastname: Ledbetter
authors.forename: J
authors.initials: J
authors.lastname: Westermann
authors.forename: I
authors.initials: I
authors.lastname: Körner
authors.forename: K
authors.initials: K
authors.lastname: Daemen
authors.forename: E A
authors.initials: EA
authors.lastname: Clark
authors.forename: A
authors.initials: A
authors.lastname: Aicher
authors.forename: A
authors.initials: A
authors.lastname: Pezzutto
mesh_terms: D018952:Antigens, CD34 / Q000276:immunology*; D001483:Base Sequence; D002454:Cell Differentiation; D017931:DNA Primers; D003713:Dendritic Cells / Q000166:cytology / Q000276:immunology*; D005786:Gene Expression Regulation / Q000502:physiology*; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000276:immunology*; D006801:Humans; D008024:Ligands; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology*; D020298:U937 Cells
chemical_list: D018952:Antigens, CD34; D017931:DNA Primers; D008024:Ligands; D014409:Tumor Necrosis Factor-alpha