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Background Drug provocation tests ( DPT) are commonly performed as part of β-lactam ( BL) allergy workup, in case of negative skin tests ( ST) and in the absence of contraindications. The recommendations of learned societies have created a frame for DPT performance, but protocols vary widely between centres, generating various hypothesis-driven protocols (i.e. empirical dosing, driven by both safety concerns and practical aspects). Methods The primary objective of this retrospective analysis was to detect eliciting dose thresholds (reactive doses) during BL DPT, using the survival analysis method, in order to suggest optimal step doses. Our secondary objective was to evaluate the safety of our 30-min incremental 1-day protocol. The study included all the patients explored in the Allergy Unit of the University Hospital of Montpellier (France), between September 1996 and July 2015 for a suspicion of drug hypersensitivity reaction to BLs, with negative ST and positive DPT. Results During the study period, 182 positive DPT (accounting for 171 hypersensitive patients) were analysed. We identified eliciting thresholds, and we suggest the following steps for DPT to BLs: 5-15-30-50% of daily therapeutic dose (with additional lower steps for index reactions of anaphylaxis). We confirm the safety of 1-day protocol for immediate and mild nonimmediate reactors, for both children and adults, with a surveillance period of 2 h after the last administered dose, and a prolonged surveillance after discharge of 48 h. Conclusion This data-driven approach in designing DPT protocols is a step forward in improving DPT standardization, starting with the most frequently tested drugs, BL antibiotics. [ABSTRACT FROM AUTHOR]

Background The house dust mite (HDM ) allergen Der p 13 could be a lipid-binding protein able to activate key innate signaling pathways in the initiation of the allergic response. We investigated the IgE reactivity of recombinant Der p 13 (rDer p 13), its lipid-binding activities, and its capacity to stimulate airway epithelium cells. Methods Purified rDer p 13 was characterized by mass spectrometry, circular dichroism, fluorescence-based lipid-binding assays, and in silico structural prediction. IgE-binding activity and allergenic potential of Der p 13 were examined by ELISA, basophil degranulation assays, and in vitro airway epithelial cell activation assays. Results Protein modeling and biophysical analysis indicated that Der p 13 adopts a β-barrel structure with a predominately apolar pocket representing a potential binding site for hydrophobic ligands. Fluorescent lipid-binding assays confirmed that the protein is highly selective for ligands and that it binds a fatty acid with a dissociation constant typical of lipid transporter proteins. The low IgE-binding frequency (7%, n = 224) in Thai HDM-allergic patients as well as the limited propensity to activate basophil degranulation classifies Der p 13 as a minor HDM allergen. Nevertheless, the protein with its presumptively associated lipid(s) triggered the production of IL-8 and GM-CSF in respiratory epithelial cells through a TLR2-, MyD88-, NF-kB-, and MAPK-dependent signaling pathway. Conclusions Although a minor allergen, Der p 13 may, through its lipid-binding capacity, play a role in the initiation of the HDM-allergic response through TLR2 activation. [ABSTRACT FROM AUTHOR]