title: Interferon-γ regulates growth and controls Fcγ receptor expression and activation in human intestinal mast cells.
abstract: BACKGROUND
  Development and function of tissue resident mast cells (MCs) is tightly controlled by various cytokines, most of which belong to the typical T helper (Th) 2-type cytokines such as IL-3 and IL-4. The effects of the Th1-type cytokine IFN-γ on human MCs is less clear.
  
  
  RESULTS
  Here, we analyzed the effects of IFN-γ on tissue-derived, mature human MCs. We found that INF-γ decreases proliferation, without affecting apoptosis in human intestinal MCs cultured in the presence of optimal concentrations of stem cell factor (SCF) or SCF and IL-4. However, in the absence of growth factors or at suboptimal concentrations of SCF, INF-γ promotes survival through inhibition of MC apoptosis. Interestingly, we found that INF-γ has no effect on FcϵRI expression and FcϵRI-mediated release of histamine and leukotriene (LT)C4, while it has profound effects on FcγR expression and activation. We show that intestinal MCs express FcγRI, FcγRIIa, and FcγRIIc, whereas FcγRIIb expression was found in only 40% of the isolates and FcγRIII was never detectable. INF-γ strongly increases FcγRI and decreases FcγRIIa expression. INF-γ-naïve MCs produce LTC4 but fail to degranulate upon crosslinking of surface-bound monomeric IgG. In contrast, INF-γ-treated MCs rapidly release granule-stored histamine in addition to de novo-synthesized LTC4.
  
  
  CONCLUSIONS
  In summary, we identify INF-γ as an important regulator of tissue-resident human MCs. IFN-γ displays a dual function by blocking extensive MC proliferation, while decreasing apoptosis in starving MCs and enhancing FcγRI expression and activation. These results emphasize the involvement of mucosal MCs in Th1-mediated disorders.
authors.affiliation: Department of Internal Medicine III, University Hospital Aachen, RWTH University, Aachen, Germany. gsellge@ukaachen.de.
authors.forename: Gernot
authors.initials: G
authors.lastname: Sellge
authors.forename: Miriam
authors.initials: M
authors.lastname: Barkowsky
authors.forename: Sigrid
authors.initials: S
authors.lastname: Kramer
authors.forename: Thomas
authors.initials: T
authors.lastname: Gebhardt
authors.forename: Leif E
authors.initials: LE
authors.lastname: Sander
authors.forename: Axel
authors.initials: A
authors.lastname: Lorentz
authors.forename: Stephan C
authors.initials: SC
authors.lastname: Bischoff
mesh_terms: D017209:Apoptosis / Q000187:drug effects / Q000276:immunology; D002454:Cell Differentiation / Q000187:drug effects / Q000276:immunology; D049109:Cell Proliferation / Q000187:drug effects; D005786:Gene Expression Regulation / Q000187:drug effects; D006632:Histamine / Q000096:biosynthesis; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology / Q000378:metabolism; D007371:Interferon-gamma / Q000494:pharmacology*; D007422:Intestines / Q000276:immunology*; D008407:Mast Cells / Q000166:cytology / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism*; D011485:Protein Binding; D017455:Receptors, IgE / Q000378:metabolism; D017452:Receptors, IgG / Q000235:genetics / Q000378:metabolism*
chemical_list: D007074:Immunoglobulin G; D017455:Receptors, IgE; D017452:Receptors, IgG; D006632:Histamine; D007371:Interferon-gamma