Search

Allergy is one of the world's most common chronic conditions. The state of the art method for allergy testing is the skin prick test (SPT) where different allergens are introduced into the skin of the tested person. This method is at best semi- quantitative, a relatively low number of tests can be performed and patients might experience unpleasant reactions. This invention is a novel allergy test providing fast, accurate and quantitative monitoring of allergic reactions in the skin. As a novelty, microneedle-based electrochemical sensor arrays are used to introduce allergens in the skin and perform electrochemical detection of biomarkers released from activated mast cells in the interstitial fluid.

Recruitment to the local tissue and alerted phenotype are the hallmarks of basophils in chronic urticaria (CU). Chemokine receptors such as chemokine (C-C motif) receptor 4 (CCR4) or CCR8 have been studied in skin diseases, e.g., atopic dermatitis, but not in CU. In this study, we aimed to define CU's basophil homing potential and receptor profile and the effect of Omalizumab treatment on these. Unstimulated and activated (anti-IgE, fMLP, C5a, and Substance P) whole blood basophils from 11 Omalizumab-treated CU patients and 10 healthy subjects were investigated with flow cytometry. Unstimulated basophils in CU showed higher expression of the skin-associated (CCR8) and scavenger (CCX-CKR) receptors and lower expression of the lung-associated (CCR3) receptor in contrast to healthy ones. IgE-mediated activation increased the percentage of CCR8 and CCX-CKR in CU compared to healthy group and elevated the expression of the lung-associated chemokine receptor, XCR1, in all groups. A trend of augmented expression of the coagulation cascade (CD87) and fMLP (FPR1) receptors was seen on basophils in CU, while a tendency of reduced expression was seen for itch (IL-31RA) and immunotolerance (CD109) receptors. fMLP and C5a increased the expression of CCR4, CCR8, CCX-CKR, and CD87 and decreased CCR2 and CCR3, though no changes between the groups were found. In conclusion, CU basophils exhibit skin-homing potential amplified by IgE-mediated stimulation.

Background: The basophil histamine release (HR) assay can be used for allergy diagnosis in addition to the conventional measurement of allergen-specific IgE (sIgE). Passive sensitization of basophils increases the versatility and allows testing the biological relevance of allergen-induced IgE cross-linking in any serum unbiased by the cellular component. However, not all the patient sera perform equally well and we hypothesized that the absolute level and fraction of sIgE affect the performance. Choosing birch pollen allergy as a model, we investigated the concentration of sIgE needed for successful passive sensitization using soluble- or matrix-fixed Bet v 1.Methods: Twenty-eight sera with Bet v 1 sIgE [7 sera within each allergy class (1: 0.1-0.70 kUA/L, 2: 0.71-3.50 kUA/L, 3: 3.51-17.50 kUA/L, and 4+: >17.50 kUA/L)] and a negative control serum pool were used to passively sensitize donor basophils, obtained from buffy coat blood ( n = 3). The cells were incubated (30 min) with a soluble allergen (rBet v 1 from 0.2 to 50 ng/ml), matrix-fixed allergen (ImmunoCAP™ containing recombinant Bet v 1), or phorbol 12-myristate 13-acetate (PMA)/ionomycin mixture (maximal HR) and released histamine was quantified fluorometrically. Results: The lowest level of Bet v 1 sIgE generating a detectable HR (HR > 10% of maximal release) in all the 3 runs was found to be 1.25 kUA/L (corresponding to allergy class 2, 0.71-3.50 kUA/L). Furthermore, sera from allergy classes 3 and 4+ ascertained a significant reproducible HR: 42/42 vs. 5/21 in allergy class 1 and 15/21 in allergy class 2. Using ImmunoCAP™s containing Bet v 1 as a matrix-fixed allergen system, similar results were obtained where the lowest sIgE concentration mediating an HR was 1.68 kUA/L and 7/7 for both allergy classes 3 and 4+.Conclusion: The results demonstrate that the IgE titer is strikingly robust in predicting the ability to sensitize basophils and produce a measurable HR.

BACKGROUND: Polyethylene glycols (PEGs) are polymers of varying molecular weight (MW) used widely as excipients in drugs and products, including the mRNA vaccines against COVID-19. Allergy to PEGs is very rare. Skin testing and graded challenge carries a high risk of inducing systemic reactions.OBJECTIVE: To evaluate skin prick test (SPT) and in-vitro reactivity over time to different MW PEGs and assess cross-sensitization patterns in PEG allergy.METHODS: Ten patients with previously diagnosed PEG allergy were skin prick tested twice with PEGs 26 months apart. Lower MW (PEG 300, 3000, 6000) were tested, followed by PEG 20,000 in stepwise, increasing concentrations. Cross-sensitization to polysorbate 80 and poloxamer 407 was assessed. SPT was performed in 16 healthy controls. In vitro Basophil Histamine Release (HR) test and passive sensitization HR test were performed in patients and controls.RESULTS: Patients previously testing positive on SPT to PEG 3000 and/or 6000 also tested positive to PEG 20,000. Patients with longer interval since diagnosis tested negative to lower MW PEGs and positive mainly to higher concentrations of PEG 20,000. Three patients developed systemic urticaria during SPT. Eight patients showed cross-sensitization to poloxamer 407 and three to polysorbate 80. All controls tested negative. In-vitro tests showed limited usefulness.CONCLUSION: Skin test reactivity to PEG can decrease over time, but titrated SPT with increasing concentrations of PEG 20,000 can be diagnostic when lower MW PEGs test negative. To avoid systemic reactions stepwise SPT is mandatory.CLINICAL IMPLICATIONS: An algorithm using a stepwise approach of skin prick testing to PEGs of increasing molecular weights and concentrations can be used to diagnose allergy to PEGs.

A highly sensitive amperometric Prussian blue-based hydrogen peroxide sensor was developed using 3D pyrolytic carbon microelectrodes. A 3D printed multielectrode electrochemical cell enabled simultaneous highly reproducible Prussian blue modification on multiple carbon electrodes. The effect of oxygen plasma pre-treatment and deposition time on Prussian blue electrodeposition was studied. The amperometric response of 2D and 3D sensors to the addition of hydrogen peroxide in µM and sub-µM concentrations in phosphate buffer was investigated. A high sensitivity comparable to flow injection systems and a detection limit of 0.16 µM was demonstrated with 3D pyrolytic carbon microelectrodes at stirred batch condition.

Human anaphylactic reactions largely involve an increase in vascular permeability, which is mainly controlled by endothelial cells (ECs). Due to the acute and serious nature of human anaphylaxis, in vivo studies of blood vessels must be replaced or supplemented with in vitro models. Therefore, we used a macromolecular tracer assay (MMTA) to investigate the EC permeability of three phenotypes of human ECs: artery (HAECs), vein (HSVECs) and microvessels from lung (HMLECs). ECs were stimulated with two fast-acting anaphylactic mediators (histamine and platelet-activating factor (PAF)) and one longer-lasting mediator (thrombin). At steady-state conditions, HSVEC monolayers were the most permeable and HMLEC the least (15.8% and 8.3% after 60 min, respectively). No response was found in ECs from artery or vein to any stimuli. ECs from microvessels reacted to stimulation with thrombin and also demonstrated a tendency of increased permeability for PAF. There was no reaction for histamine. This was not caused by missing receptor expression, as all three EC phenotypes expressed receptors for both PAF and histamine. The scarce response to fast-acting mediators illustrates that the MMTA is not suitable for investigating EC permeability to anaphylactic mediators.

Basophils have been suggested to express low quantities of RNA, challenging the study of gene expression within these cells. However, the purification technique employed might have an impact on the quantity and quality of RNA purified from basophils. This chapter describes a method which gives an optimal RNA output using a TRIzol-based method in contrast to a commercial kit.

SCOPE: Allergies to lipid transfer proteins involve severe adverse reactions; thus, effective and sustainable therapies are desired. Previous attempts disrupting disulfide bonds failed to maintain immunogenicity; thus, the aim is to design novel hypoallergenic Pru p 3 variants and evaluate the applicability for treatment of peach allergy.METHODS AND RESULTS: Pru p 3 proline variant (PV) designed using in silico mutagenesis, cysteine variant (CV), and wild-type Pru p 3 (WT) are purified from Escherichia coli. Variants display homogenous and stable protein conformations with an altered secondary structure in circular dichroism. PV shows enhanced long-term storage capacities compared to CV similar to the highly stable WT. Using sera of 33 peach allergic patients, IgE-binding activity is reduced by 97% (PV) and 71% (CV) compared to WT. Both molecules show strong hypoallergenicity in Pru p 3 ImmunoCAP cross-inhibition and histamine release assays. Immunogenicity of PV is demonstrated with a phosphate-based adjuvant formulation in a mouse model.CONCLUSIONS: An in silico approach is used to generate a PV without targeting disulfide bonds, T cell epitopes, or previously reported IgE epitopes of Pru p 3. PV is strongly hypoallergenic while structurally stable and immunogenic, thus representing a promising candidate for peach allergen immunotherapy.