title: Lack of CD24 expression in mice reduces the number of leukocytes in the colon.
abstract: CD24 is an extensively glycosylated membrane protein that is linked to the membrane via a glycosyl-phosphatidylinositol (GPI)-anchor. In mice, CD24 is expressed by hematopoietic and non-hematopoietic cells. CD24-/- mice do not have gross immunological defects, but detailed analysis revealed strongly reduced responses in an experimental autoimmune encephalomyelitis (EAE) model and a massive proliferation of T cells under lymphopenic conditions. It was also demonstrated that preB cells from CD24-/- mice are impaired in α4-integrin-mediated cell binding. Here we report that CD24-/- mice have strongly reduced numbers of leukocytes in the colon compared to wildtype mice. The reduction comprized all subpopulations. Leukocyte counts in spleen, mesenteric lymph nodes or small intestine were not significantly different. We find that beside leukocytes, CD24 is widely expressed in EpCAM+ epithelial and CD31+ endothelial cells of colon and small intestine. However, in CD24-/- mice the number of CD31+ endothelial cells in colons was strongly reduced and the number of epithelial cells was augmented. Leukocyte transfer experiments provided evidence that the CD24 status of recipient mice, rather than of the transferred cells, is crucial for leukocyte recruitment to the colon. We hypothesize that CD24 on colonic epithelial and endothelial cells is required for the retention and positioning of leukocytes most likely by affecting integrin function.
authors: Tumor Immunology Programme, D015, German Cancer Research Center (DKFZ), D-69120 Heidelberg, Germany.
authors: Niko P
authors: NP
authors: Bretz
authors: Tumor Immunology Programme, D015, German Cancer Research Center (DKFZ), D-69120 Heidelberg, Germany.
authors: Alexei V
authors: AV
authors: Salnikov
authors: Tumor Immunology Programme, D015, German Cancer Research Center (DKFZ), D-69120 Heidelberg, Germany.
authors: Kai
authors: K
authors: Doberstein
authors: Department of Molecular Immunology, Institutes of Molecular Medicine and Experimental Immunology, University of Bonn, Bonn, Germany.
authors: Natalio
authors: N
authors: Garbi
authors: Tumor Immunology Programme, D015, German Cancer Research Center (DKFZ), D-69120 Heidelberg, Germany.
authors: Volker
authors: V
authors: Kloess
authors: Tumor Immunology Programme, D015, German Cancer Research Center (DKFZ), D-69120 Heidelberg, Germany.
authors: Safwan
authors: S
authors: Joumaa
authors: The Integrated Cancer Prevention Center, Tel Aviv Medical Center, Tel Aviv University, Israel.
authors: Inna
authors: I
authors: Naumov
authors: Bioceros Holding BV, Utrecht, The Netherlands.
authors: Louis
authors: L
authors: Boon
authors: Tumor Immunology Programme, D015, German Cancer Research Center (DKFZ), D-69120 Heidelberg, Germany.
authors: Gerhard
authors: G
authors: Moldenhauer
authors: The Integrated Cancer Prevention Center, Tel Aviv Medical Center, Tel Aviv University, Israel.
authors: Nadir
authors: N
authors: Arber
authors: Tumor Immunology Programme, D015, German Cancer Research Center (DKFZ), D-69120 Heidelberg, Germany. Electronic address: P.Altevogt@dkfz.de.
authors: Peter
authors: P
authors: Altevogt
mesh_terms: D000818:Animals; D051927:CD24 Antigen / Q000235:genetics*; D002452:Cell Count; D002634:Chemotaxis, Leukocyte / Q000235:genetics / Q000276:immunology; D003106:Colon / Q000276:immunology / Q000473:pathology*; D016207:Cytokines / Q000378:metabolism; D042783:Endothelial Cells / Q000378:metabolism; D015870:Gene Expression; D016130:Immunophenotyping; D007413:Intestinal Mucosa / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D007962:Leukocytes / Q000276:immunology / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout
chemical_list: D051927:CD24 Antigen; D016207:Cytokines
keywords: Adressin; CD24; Chemokines; Cytokines; Integrins