Introduction
Anaphylaxis is an acute multi-organ hypersensitivity reaction that can rapidly progress to a severe life-threatening reaction.It occurs upon exposure to allergens，for example food，aeroallergens，venom，drugs，and immunizations.The incidence of anaphylaxis has been increasing over the past few decades［1- 3］.Recent estimates suggest a lifetime prevalence of 0.05% to 2.0% with food anaphylaxis being the most common cause［1，4，5］.Currently，the clinical definition of anaphylaxis is controversial，because of the non-specificity of symptoms and the variability of presentation.Routine diagnostic methods of anaphylaxis are based on indirect detection tools using several laboratory markers［6］.Immunochemical and biochemical mediators released during anaphylaxis are detected as diagnostic adjuncts，for example IgE antibodies，histamine，prostaglandin D2，carpoxypeptidase，CD63，interleukins 4 and 6，C-reactive protein(CRP)，and tryptase［6- 8］.However，these methods have limitations because of the complexity and diversity of anaphylaxis.Simultaneous determination of metabolic change in anaphylaxis might be helpful in understanding its pathophysiological processes and diagnosis.
Metabolomics is a method of investigating metabolic pathways and identifying unique biochemical molecules generated in a living system［9］.It may provide an overview of the dynamic metabolic status of the organism and yield new biomarkers which can be a clinic tool for diagnosis of disease［9］.Metabolic profiling is a complementary approach for metabolomic investigations［10］.It has been applied in studies investigating the metabolic response to various diseases，for example pre-eclampsia［11］，Huntington's disease［12］，Parkinson's disease［13］，prostate cancer［14］，human hepatocellular carcinoma［15］，diabetes［16］，intrauterine growth restriction(IUGR)［17］，but not anaphylaxis.(https://www.daowen.com)
The most commonly used techniques in metabolomic analysis are nuclear magnetic resonance(NMR)spectroscopy，Fourier-transform infrared spectroscopy(FT-IR)，and mass spectrometry(MS)［18］.MS-based metabolomics，including gas chromatographymass spectrometry(GC-MS)，gas chromatography-tandem mass spectrometry(GC-MS-MS)，liquid chromatography-mass spectrometry(LC-MS)，liquid chromatography-tandem mass spectrometry(LC-MS-MS)，and capillary electrophoresis-mass spectrometry(CE-MS)enable highly efficient separation，sensitive quantitative analysis，and use of MS databases for metabolite identification［10，19］.Among these，GC-MS has been widely used in metabolomics because of its widespread availability，high resolution，and reproducibility［19］.
The purpose of this study was to generate GC-MSserum metabolic profiles for anaphylaxis animal models and search for differences between control and model groups by use of pattern-recognition techniques.This would be helpful in identifying potential biomarkers for application in clinical diagnosis and monitoring of anaphylaxis.