title: Understanding the mechanisms of anaphylaxis.
abstract: OBJECTIVE
  The present review considers recent reports that identify the roles of key intermediate signaling components and mediators during and after mast cell activation and degranulation leading to anaphylaxis.
  
  
  RESULTS
  Mechanisms of anaphylaxis are becoming better understood as the interaction of several regulatory systems in the mast cell activation and degranulation signaling cascade. Multiple tyrosine kinases, activated after immunoglobulin E binding to the high-affinity receptors for immunoglobulin E (FcepsilonRI), exert both positive and negative regulation on the signaling cascade, which may vary with genetic background or mutations in signaling proteins. Calcium influx, the essential, proximal intracellular event leading to mast cell degranulation, is controlled also by both negative and positive regulation through calcium channels. Sphingosine-1-phosphate is emerging as a newly realized mediator of anaphylaxis, acting as a signaling component within the mast cell and as a circulating mediator.
  
  
  CONCLUSIONS
  Anaphylaxis is a systemic reaction involving multiple organ systems, but it is believed that it may be influenced by cellular events in mast cells and basophils resulting in the release of mediators. Therefore, understanding the mechanisms of mast cell activation and degranulation is critical to understanding the mechanisms of anaphylaxis. Recent reports have identified important regulatory components of the signaling cascade and, consequently, potential targets for therapeutic intervention.
authors.affiliation: Laboratory of Allergic Diseases, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892-1881, USA. peavyr@niaid.nih.gov
authors.forename: Richard D
authors.initials: RD
authors.lastname: Peavy
authors.forename: Dean D
authors.initials: DD
authors.lastname: Metcalfe
mesh_terms: D000707:Anaphylaxis / Q000235:genetics / Q000276:immunology / Q000503:physiopathology; D000818:Animals; D015220:Calcium Channels / Q000276:immunology; D015550:Cell Degranulation / Q000235:genetics / Q000276:immunology; D006801:Humans; D007073:Immunoglobulin E / Q000096:biosynthesis / Q000276:immunology; D018836:Inflammation Mediators / Q000276:immunology; D008246:Lysophospholipids / Q000276:immunology; D008407:Mast Cells / Q000276:immunology* / Q000378:metabolism; D034721:Mastocytosis, Systemic / Q000235:genetics / Q000276:immunology / Q000503:physiopathology; D051379:Mice; D051076:Proto-Oncogene Proteins c-fyn / Q000235:genetics / Q000276:immunology; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology; D013110:Sphingosine / Q000031:analogs & derivatives / Q000276:immunology; D019061:src-Family Kinases / Q000235:genetics / Q000276:immunology
chemical_list: D015220:Calcium Channels; D018836:Inflammation Mediators; D008246:Lysophospholipids; C060506:sphingosine 1-phosphate; D007073:Immunoglobulin E; C494957:FYN protein, human; D051076:Proto-Oncogene Proteins c-fyn; C060902:lyn protein-tyrosine kinase; D019061:src-Family Kinases; D013110:Sphingosine