Omalizumab efficacy in cases of chronic spontaneous urticaria is not explained by the inhibition of sera activity in effector cells.

Omalizumab (OmAb) is a humanized anti-IgE antibody approved for the treatment of chronic spontaneous urticaria (CSU). OmAb's mechanism of action is known to include actions on free IgE and on pre-bound IgE. However, OmAb is equally and rapidly effective against autoimmune and non-autoimmune urticaria where IgE involvement is not clear, suggesting the involvement of additional mechanisms of action. In this study, we sought to investigate the ability of OmAb to inhibit mast cell and basophil degranulation induced by sera from CSU patients. For this purpose, we performed a comparison between the in vitro incubation of sera from CSU patients treated with OmAb and the in vivo administration of OmAb in a clinical trial. We found that OmAb added in vitro to sera from CSU patients did not modify the ability of the sera to induce cell degranulation. Similarly, the sera from patients treated with OmAb in the context of the clinical trial who had a good clinical outcome maintained the capacity to activate mast cells and basophils. Thus, we conclude that the beneficial activity of OmAb does not correlate with the ability of patient sera to induce cell degranulation.

Clinical performance of commercial ISAC 112 allergen microarray versus noncommercial RIRAAF platform for the diagnosis of plant food and olive pollen allergies

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Is the determination of specific IgE against components using ISAC 112 a reproducible technique?

BACKGROUND: The ImmunoCAP ISAC 112 is a fluoro-immunoassay that allows detection of specific IgE to 112 molecular components from 51 allergenic sources. We studied the reliability of this technique intra- and inter- assay, as well as inter-batch- and inter-laboratory-assay. METHODS: Twenty samples were studied, nineteen sera from polysensitized allergic patients, and the technique calibrator provided by the manufacturer (CTR02). We measured the sIgE from CTR02 and three patients' sera ten times in the same and in different assays. Furthermore, all samples were tested in two laboratories and with two batches of ISAC kit. To evaluate the accuracy of ISAC 112, we contrasted the determinations of CTR02 calibrator with their expected values by T Student test. To analyse the precision, we calculated the coefficient of variation (CV) of the 15 allergens that generate the calibration curve, and to analyse the repeatability and the reproducibility, we calculated the intraclass coefficient correlation (ICC) to each allergen. RESULTS: The results obtained for CTR02 were similar to those expected in 7 of 15 allergens that generate the calibration curve, whereas in 8 allergens the results showed significant differences. The mean CV obtained in the CTR02 determinations was of 9.4%, and the variability of sera from patients was of 22.9%. The agreement in the intra- and inter-assay analysis was very good to 94 allergens and good to one. In the inter-batch analyse, we obtained a very good agreement to 82 allergens, good to 14, moderate to 5 allergens, poor to one, and bad to 1 allergen. In the inter-laboratory analyse, we obtained a very good agreement to 73 allergens, good to 22, moderate to 6 and poor to two allergens. CONCLUSION: The allergen microarray immunoassay, ISAC 112, is a repeatable and reproducible in vitro diagnostic tool for determination of sIgE beyond the own laboratory.

Decrease in antigen-specific CD63 basophil expression is associated with the development of tolerance to egg by SOTI in children.

BACKGROUND: In the last decade, there have been an increasing number of studies on achieving tolerance to foods by specific oral tolerance induction (SOTI). Still, the underlying mechanism of SOTI is unknown. Our aim was to describe changes in CD63 expression on basophils following in vitro Ag-specific stimulation by basophil activation test (BAT), after SOTI with egg in a pediatric population. METHODS: Ten children with persistent allergy to egg were included. Skin prick tests (SPTs) and open food challenges (OFCs) were performed before SOTI. Specific IgE determination and BAT with egg white (EW), ovomucoid (OM), and ovalbumin (OVA) were performed before and after 1 month of the buildup phase of SOTI. RESULTS: Total tolerance to egg was achieved in 9 cases and partial in one. After SOTI, there was a significant decrease in mean specific IgE levels (p < 0.05). CD63 expression also decreased (p < 0.05) in all patients. CONCLUSION: Decrease in Ag-specific basophil responsiveness is associated with the development of clinical tolerance by SOTI.