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Diagnosing immediate drug hypersensitivity reactions (IDHRs) can pose a significant challenge and there is an urgent need for safe and reliable tests. Evidence has emerged that the basophil activation test (BAT), an in vitro assay that mirrors the in vivo response, can be a complementary test for many drugs. In this position paper, members of Task Force (TF) "Basophil activation test in the evaluation of Drug Hypersensitivity Reactions" from the European Academy of Allergy and Clinical Immunology (EAACI) present the data from a survey about the use and utility of BAT in IDHRs in Europe. The survey results indicate that there is a great interest for using BAT especially for diagnosing IDHRs. However, there are still main needs, mainly in the standardization of the protocols. Subsequently consensus‐based recommendations were formulated for: (i) Technical aspects of BAT in IDHRs including type of sample, management of drugs, flow cytometry protocols, interpretation of the results; and (ii) Drug‐specific aspects that should be taken into account when performing BAT in relation to betalactams, neuromuscular blocking agents, fluoroquinolones, chlorhexidine, opioids, radio contrast media, chemotherapeutics, biological agents, nonsteroidal anti‐inflammatory drugs, COVID vaccine, and excipients. Moreover, aspects in the evaluation of pediatric population have also been considered. All this indicates that BAT offers the clinician and laboratory a complementary tool for a safe diagnostic for IDHRs, although its place in the diagnostic algorithm depends on the drug class and patient population (phenotype, geography, and age). The standardization of BAT is important for generalizing this method beyond the individual laboratory. [ABSTRACT FROM AUTHOR]

The article discusses the basophil activation test (BAT) as a diagnostic tool for managing patients with IgE-mediated allergies. The authors emphasize the need for standardization and external quality assurance (EQA) of laboratory protocols and results interpretation. A task force was created to develop a consensus protocol for BAT-EQA, and round robin tests were conducted to train participating laboratories. The article presents a proposed standard operating protocol for BAT and highlights the importance of EQA for routine implementation of the assay. The authors conclude that the consensus protocol provides acceptable inter- and intralaboratory variability and can be implemented across Europe. [Extracted from the article]

Mast cells have long been recognized as the principal cell type that initiates the inflammatory response characteristic of acute allergic type 1 reactions. Our goal has been to further characterize maturation of progenitors to mast cells.Mast cells were cultured from human cord blood derived CD133+ progenitors. Mast cell function was tested using histamine release. During differentiation mast cells surface marker expression was monitored by flow cytometry.CD133+ progenitors expressed the early haematopoietic and myeloid lineage markers CD34, CD117, CD13 and CD33. Mature mast cells expressed CD117, CD13 and CD33, and expression of the high affinity immunoglobulin E recpetor FcℇRI increased during culture. Cytokine receptors interleukin (IL)-5R, IL-3R,granulocyte-macrophage-colony stimulating factor (GM-CSF)R and IL-18R were expressed at high levels during maturation. Chemokine receptors CXCR4 and CXCR2 were highly expressed on both newly purified CD133+ cells and mature cells.Human mast cells can be cultured from a CD34+/CD117+/CD13+/CD33+ progenitor cell population in cord blood that is tryptase and chymase negative. Developing and mature mast cells express a wide range of chemokine and cytokine receptors. We found high levels of expression of CD123, IL-5R and GM-CSF receptors, also found on eosinophils and basophils, and high levels of expression of the receptor for the inflammatory cytokine IL-18. [ABSTRACT FROM AUTHOR]