title: Ontogenic changes in CD95 expression on human leukocytes: prevalence of T-cells expressing activation markers and identification of CD95-CD45RO+ T-cells in the fetus.
abstract: The ontogeny of the human immune system was studied by analyzing fetal and adult tissues for the presence of various lymphocyte populations and activation/maturation markers. CD95 (fas) was expressed in hematopoietic tissues during the final stages of development of monocytes, granulocytes, NK cells and T cells, but to a much lesser extent on B cells. In the periphery, CD95 expression declined on granulocytes and NK cells. CD95 was expressed at a higher level on CD45RA+ peripheral T-cells in the fetus than in the adult. Contrary to the belief that most fetal T-cells are naïve or resting, a notable number of CD45RO+ T-cells were observed as well as an unique CD95-CD45RO+ population. Activation markers CD25, CD122, CD69 and CD80 were also present on fetal T-cells. These findings indicate that in the initial weeks following thymic maturation, a high frequency of T-cells is activated in the periphery of the fetus.
authors.affiliation: Department of Laboratory Medicine, University of California, 533 Parnassus Ave., 94143-0793, San Francisco, CA, USA
authors.forename: Marcus O
authors.initials: MO
authors.lastname: Muench
authors.forename: Eva M
authors.initials: EM
authors.lastname: Pott Bärtsch
authors.forename: Jeng-Chang
authors.initials: JC
authors.lastname: Chen
authors.forename: John B
authors.initials: JB
authors.lastname: Lopoo
authors.forename: Alicia
authors.initials: A
authors.lastname: Bárcena
mesh_terms: D000328:Adult; D000375:Aging / Q000276:immunology*; D015415:Biomarkers / Q000032:analysis; D005333:Fetus / Q000276:immunology*; D005434:Flow Cytometry; D006801:Humans; D016130:Immunophenotyping; D017493:Leukocyte Common Antigens / Q000378:metabolism*; D008213:Lymphocyte Activation; D020033:Protein Isoforms / Q000378:metabolism; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000378:metabolism; D018121:Receptors, Cytokine / Q000378:metabolism; D013601:T-Lymphocytes / Q000378:metabolism*; D019014:fas Receptor / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D020033:Protein Isoforms; D016693:Receptors, Antigen, T-Cell, alpha-beta; D018121:Receptors, Cytokine; D019014:fas Receptor; D017493:Leukocyte Common Antigens