62 research outputs found
Laboratorial approach in the diagnosis of food allergy
OBJCTIVE: Review the available laboratory tests used to assist in the diagnosis of IgE-mediated and non-IgE-mediated food allergy. DATA SOURCES: Papers in English and Portuguese published in PubMed and Embase, in the last ten years. Terms searched were food allergy, diagnose and laboratory, isolated and/or associated. DATA SYNTHESIS: The diagnostic approach to food allergy reactions includes a good medical history, laboratory studies, elimination diets and blinded food challenges. More recently, the use of a quantitative measurement of food-specific IgE antibodies has been shown to be more predictive of symptomatic IgE-mediated food allergy. Food-specific IgE serum levels exceeding the diagnostic values indicate that the patient is greater than 95% likely to experience an allergic reaction if he/she ingests the specific food. Such decision point values have been defined just for some foods and inconsistent results were obtained when allergy to the same food was studied in different centers. Food challenges, in particular the double-blind placebo-controlled food challenge (DBPCFC), represent the most reliable way to establish or rule out food hypersensitivity. CONCLUSIONS: A number of recent developments are improving the predictive value of some laboratory tests for the diagnosis of food allergies. However, to date, no in-vitro or in-vivo test shows full correlation with clinical food allergy and the DBPCFC remains the gold standard for the definitive diagnosis of specific food allergies. There is an urgent need for new and fundamentally improved diagnostic approaches, which must be validated in patients with food allergy confirmed by a positive DBPCFC.OBJETIVO: Revisar os exames laboratoriais disponĂveis utilizados no diagnĂłstico da alergia alimentar mediada ou nĂŁo por IgE. FONTES DE DADOS: Artigos publicados em base de dados PubMed e Embase (lĂngua inglesa e portuguesa) nos Ăşltimos dez anos. As palavras-chave utilizadas como fonte de busca foram alergia alimentar, diagnĂłstico e laboratĂłrio, isolados e/ou associados. SĂŤNTESE DOS DADOS: A abordagem diagnĂłstica das reações alĂ©rgicas a alimentos inclui histĂłria clĂnica completa, estudos laboratoriais, dietas de eliminação e desencadeamentos cegos com alimentos. Recentemente, a medida quantitativa de anticorpos IgE especĂficos a alimentos tem mostrado ser mais preditiva de alergia alimentar sintomática mediada por IgE. NĂveis sĂ©ricos de IgE especĂfica a alimento que excedam os valores diagnĂłsticos indicam que o paciente tem chance maior que 95% de apresentar uma reação alĂ©rgica se ingerir o alimento em questĂŁo. Estes valores de decisĂŁo foram definidos para alguns alimentos e resultados inconsistentes sĂŁo obtidos ao se estudar diferentes populações. Os desencadeamentos com alimento, especialmente o duplo-cego controlado por placebo (DADCCP), representa a maneira mais confiável de estabelecer ou descartar o diagnĂłstico de hipersensibilidade alimentar. CONCLUSĂ•ES: NĂşmero crescente de aquisições tem melhorado o valor preditivo de alguns testes laboratoriais empregados no diagnĂłstico de alergias alimentares. Entretanto, atĂ© hoje, nĂŁo há teste in vitro ou in vivo que mostre correlação completa com a clĂnica da alergia alimentar. O DADCCP continua sendo o padrĂŁo-ouro no diagnĂłstico definitivo de alergia alimentar especĂfica. SĂŁo necessárias, urgentemente, novas abordagens diagnĂłsticas válidadas em pacientes com alergia alimentar confirmada por DADCCP positivo.Universidade Federal de SĂŁo Paulo (UNIFESP) Escola Paulista de Medicina Departamento de PediatriaUNIFESP-EPM Departamento de PediatriaUniversidade de SĂŁo Paulo Faculdade de Medicina Departamento de PediatriaUniversidade Federal da Bahia Departamento de PediatriaUNIFESP-EPMUniversidade Federal do Paraná Departamento de PediatriaUNIFESP, EPM, Depto. de PediatriaUNIFESP, EPM Depto. de PediatriaUNIFESP, EPMSciEL
Rapid Analysis of Listeria monocytogenes Cell Wall Teichoic Acid Carbohydrates by ESI-MS/MS
We report the application of electrospray ionization (ESI) mass spectrometry for compositional characterization of wall teichoic acids (WTA), a major component of Gram-positive bacterial cell walls. Tandem mass spectrometry (ESI-MS/MS) of purified and chemically hydrolyzed monomeric WTA components provided sufficient information to identify WTA monomers and their specific carbohydrate constituents. A lithium matrix was used for ionization of uncharged WTA monomers, and successfully applied to analyze the WTA molecules of four Listeria strains differing in carbohydrate substitution on a conserved polyribitol-phosphate backbone structure. Carbohydrate residues such as N-acetylglucosamine or rhamnose linked to the WTA could directly be identified by ESI-MS/MS, circumventing the need for quantitative analysis by gas chromatography. The presence of a terminal N-acetylglucosamine residue tethered to the ribitol was confirmed using fluorescently labeled wheat-germ agglutinin. In conclusion, the mass spectrometry method described here will greatly facilitate compositional analysis and characterization of teichoic acids and similar macromolecules from diverse bacterial species, and represents a significant advance in the identification of serovar-specific carbohydrates and sugar molecules on bacteria
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