Autoimmune mast cell activation test as a diagnostic tool in chronic spontaneous urticariaKoren, Ana (Avtor) Dejanović, Luka (Avtor) Rijavec, Matija (Avtor) Kopač, Peter (Avtor) Bizjak, Mojca (Avtor) Zidarn, Mihaela (Avtor) Košnik, Mitja (Avtor) Korošec, Peter (Avtor) mast cell activation testLAD2chronic spontaneous urticariaomalizumabCD63 expressionfirst_pagesettingsOrder Article Reprints Open AccessArticle Autoimmune Mast Cell Activation Test as a Diagnostic Tool in Chronic Spontaneous Urticaria by Ana Koren 1,*ORCID,Luka Dejanović 1ORCID,Matija Rijavec 1,2ORCID,Peter Kopač 1,3ORCID,Mojca Bizjak 1ORCID,Mihaela Zidarn 1,3,Mitja Košnik 1,3ORCID andPeter Korošec 1,4 1 University Clinic of Respiratory and Allergic Diseases Golnik, 4204 Golnik, Slovenia 2 Biotechnical Faculty, University of Ljubljana, 1000 Ljubljana, Slovenia 3 Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia 4 Faculty of Pharmacy, University of Ljubljana, 1000 Ljubljana, Slovenia * Author to whom correspondence should be addressed. Int. J. Mol. Sci. 2024, 25(17), 9281; https://doi.org/10.3390/ijms25179281 Submission received: 25 July 2024 / Revised: 23 August 2024 / Accepted: 25 August 2024 / Published: 27 August 2024 (This article belongs to the Special Issue Progression of Allergy and Immune Response) Downloadkeyboard_arrow_down Browse Figures Review Reports Versions Notes Abstract Chronic spontaneous urticaria (CSU) is associated with skin mast cell activation, and its triggering mechanisms are not completely elucidated. Evidence suggests an autoimmune component of CSU. Our aim was to assess the usefulness of an autoimmune mast cell activation test (aiMAT) for diagnosing and differentiating CSU into different subtypes. We enrolled 43 patients with active, uncontrolled CSU before starting treatment with omalizumab and 15 controls. Patients were evaluated based on omalizumab response. aiMATs were performed using non-IgE-sensitized (NS) or myeloma IgE-sensitized (S) LAD2 cells, which were then stimulated with CSU/control sera (25 µL and 10 µL). The expression of CD63 was assessed with flow cytometry. CD63 response on NS-LAD2 was significantly increased in CSU patients compared to controls after the stimulation with 25 µL CSU/control sera (p = 0.0007) and with 10 µL CSU/control sera (p = 0.0001). The ROC curve analysis demonstrated an area under the curve (AUC) of 0.82. The cutoff for autoimmune-non-IgE-sensitized-MAT was 40.3% CD63+ LAD2, which resulted in 73.3% sensitivity and 81.4% specificity. CD63 response on S-LAD2 was significantly increased in CSU patients compared to controls after the stimulation with 25 µL CSU/control sera (p = 0.03). The ROC curve analysis demonstrated an AUC of 0.66. The cutoff for the autoimmune-myeloma IgE-sensitized-MAT was 58.4% CD63+ cells, which resulted in 62.8% sensitivity and 66.7% specificity. Overall, 36 out of 43 (84%) patients responded to omalizumab, and 7 (16%) were nonresponders. We found no differences between LAD2 CD63 response and response to omalizumab. In conclusion, aiMAT could represent a new diagnostic tool in CSU. Additional studies are needed to evaluate the potential benefits during omalizumab therapy.MDPI20242025-03-06 11:56:44Neznano21640International journal of molecular sciencessl© 2024 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).