Basophil activation test in the diagnostic procedure of IgE-mediated cow's milk allergy

• Grant number: 21/02417-2
• Support Opportunities: Regular Research Grants
• Start date: September 01, 2021
• End date: February 29, 2024
• Field of knowledge: Health Sciences - Medicine - Maternal and Child Health
• Principal Investigator: Lucila Camargo Lopes de Oliveira
• Grantee: Lucila Camargo Lopes de Oliveira
• Host Institution: Escola Paulista de Medicina (EPM). Universidade Federal de São Paulo (UNIFESP). Campus São Paulo. São Paulo , SP, Brazil
• Associated researchers: Alexandra Figueira Santos ; Dirceu Solé ; Maria Isabel de Moraes Pinto
• Associated scholarship(s): 21/14000-9 - Basophil Activation Test in the diagnostic procedure of IgE-mediated cows milk allergy, BP.TT

Abstract

Cow's milk is the most common food allergen in Brazil. Food allergies can be IgE, mixed or non-IgE mediated. IgE-mediated cow's milk allergy occurs within 2 hours of the ingestion or contact with milk protein. Among IgE-mediated manifestations, there is anaphylaxis. The presence of food specific IgE - identified by means of skin prick test or sera determination - does not imply in clinically significant food allergy. Cow's milk allergy frequently starts at first year of life and outgrows during childhood or beginning of teenage years. Supposedly, food specific IgG4 levels takes part in tolerance acquisition. Oral Food Challenge (OFC) with the culprit allergen remains the best method to overcome doubts in diagnosing food allergy or to verify if it has outgrown. However, OFC is resource-intensive and carries de risk of severe anaphylaxis reaction. Basophil is considered an effector cell on IgE- mediated allergic manifestations, and its antigen-specific activation can be measured by flow citometry (BAT- basophil activation test). Objective: assess the capability of BAT in predicting the OFC outcome. Secondarily, we aim to determine the skin prick test wheal diameter, total serum IgE and serum allergen specific IgE and serum IgG4 levels (to cow's milk and components) capable of predicting allergy by means of OFC. Methods: cross-sectional study with 65 subjects (sample calculation) from the allergy outpatient clinic of the Federal University of São Paulo (zero to 18 years old) for whom OFC were indicated (as a diagnostic procedure or to verify spontaneous tolerance acquisition). All subjects should necessarily be milk sensitized to whole milk and/or to its components. In order to improve the analysis, 20 subjects with convincing history of recent (last 6 months) IgE-mediated allergy and proven specific sensitization will be invited during the 16-months of recruting duration. Patients will be excluded if treated with anti-IgE or milk allergen specific immunotherapy, ciclosporin A or received systemic corticosteroid within the last month. All subjects will be clinically evaluated. Skin prick test and blood collection for BAT, total IgE and IgE and IgG4 specific quantifications (to cow's milk and components) will be performed. OFC with milk will be administered to all subjects -except the ones diagnosed by convincing history- according to clinical indication. It is a pioneering study in Brazil. Improvement knowledge on BAT enables further studies on other IgE-mediated reactions like, for example, to some vaccines. (AU)