The Tec family kinase, IL-2-inducible T cell kinase, differentially controls mast cell responses.
The Tec family tyrosine kinase, IL-2-inducible T cell kinase (Itk), is expressed in T cells and mast cells. Mice lacking Itk exhibit impaired Th2 cytokine secretion; however, they have increased circulating serum IgE, but exhibit few immunological symptoms of allergic airway responses. We have examined the role of Itk in mast cell function and FcepsilonRI signaling. We report in this study that Itk null mice have reduced allergen/IgE-induced histamine release, as well as early airway hyperresponsiveness in vivo. This is due to the increased levels of IgE in the serum of these mice, because the transfer of Itk null bone marrow-derived cultured mast cells into mast cell-deficient W/W(v) animals is able to fully rescue histamine release in the W/W(v) mice. Further analysis of Itk null bone marrow-derived cultured mast cells in vitro revealed that whereas they have normal degranulation responses, they secrete elevated levels of cytokines, including IL-13 and TNF-alpha, particularly in response to unliganded IgE. Analysis of biochemical events downstream of the FcepsilonRI revealed little difference in overall tyrosine phosphorylation of specific substrates or calcium responses; however, these cells express elevated levels of NFAT, which was largely nuclear. Our results suggest that the reduced mast cell response in vivo in Itk null mice is due to elevated levels of IgE in these mice. Our results also suggest that Itk differentially modulates mast cell degranulation and cytokine production in part by regulating expression and activation of NFAT proteins in these cells.
Iyer
Archana S
AS
Center for Molecular Immunology & Infectious Disease and Department of Veterinary & Biomedical Sciences, Pennsylvania State University, University Park, PA 16802, USA.
August
Avery
A
D000485:Allergens / Q000008:administration & dosage; D000818:Animals; D016026:Bone Marrow Transplantation / Q000276:immunology; D016535:Bronchial Hyperreactivity / Q000201:enzymology / Q000235:genetics / Q000276:immunology / Q000517:prevention & control; D015550:Cell Degranulation / Q000235:genetics / Q000276:immunology; D002478:Cells, Cultured; D016207:Cytokines / Q000378:metabolism; D004136:Dinitrobenzenes / Q000276:immunology; D004195:Disease Models, Animal; D006636:Histamine Release / Q000235:genetics / Q000276:immunology; D007073:Immunoglobulin E / Q000008:administration & dosage / Q000096:biosynthesis / Q000378:metabolism; D008407:Mast Cells / Q000201:enzymology* / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D020297:Mice, Congenic; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D011505:Protein-Tyrosine Kinases / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D017455:Receptors, IgE / Q000378:metabolism / Q000502:physiology; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology
D000485:Allergens; D016207:Cytokines; D004136:Dinitrobenzenes; D017455:Receptors, IgE; D007073:Immunoglobulin E; D011505:Protein-Tyrosine Kinases; C080813:emt protein-tyrosine kinase