title: CD34+ fibrocytes: morphology, histogenesis and function.
abstract: The connective tissue of virtually all human organs harbors huge amounts of resident CD34(+) fibrocytes. Recent studies have shown that CD34(+) fibrocytes derive from circulating CD14(+) monocytes. CD34(+) fibrocytes are involved in wound healing, act as antigen presenting cells and secrete a multitude of cytokines. Due to their diverse functions CD34(+) fibrocytes play a role in connective tissue diseases, pulmonary fibrosis and tumor associated stromal remodeling. Stromal remodeling precipitated by invasive carcinomas is characterized by a loss of CD34(+) expression paralleled by a gain of alpha-SMA expression in stromal cells resulting in a phenotype change from CD34(+) fibrocytes towards alpha-SMA positive myofibroblasts. This process is very stereotypic and may play an essential role in local tumor invasion and systemic dissemination, since a reduction of antigen presenting CD34(+) fibrocytes might constitute a step in escaping the hosts' immune control directed against invasive carcinoma cells.
authors.affiliation: Institute of Pathology University Hospital Giessen and Marburg GmbH, Location Marburg, Medical Faculty of Philipps-University Marburg, Baldingerstrasse, 35033 Marburg, Germany. barthp@mailer.uni-marburg.de
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Barth
authors.forename: Christina C
authors.initials: CC
authors.lastname: Westhoff
mesh_terms: D000818:Animals; D018952:Antigens, CD34 / Q000032:analysis*; D048430:Cell Shape; D003238:Connective Tissue / Q000502:physiology*; D003239:Connective Tissue Cells / Q000166:cytology* / Q000502:physiology*; D006801:Humans; D009369:Neoplasms / Q000473:pathology; D017154:Stromal Cells / Q000166:cytology* / Q000502:physiology*
chemical_list: D018952:Antigens, CD34