{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,28]],"date-time":"2026-09-28T16:25:23Z","timestamp":1790612723446,"version":"4.1.0"},"reference-count":40,"publisher":"MDPI AG","issue":"15","license":[{"start":{"date-parts":[[2025,8,4]],"date-time":"2025-08-04T00:00:00Z","timestamp":1754265600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Johannes Kepler University Linz","award":["Impetus I-05-22 METOI"],"award-info":[{"award-number":["Impetus I-05-22 METOI"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJMS"],"abstract":"<jats:p>Specific venom immunotherapy (VIT) in patients with hymenoptera venom allergy (HVA) represents a well-studied approach to reduce the severity of a possible anaphylactic reaction. Currently, data on mechanisms of tolerance induction at the cellular level within the first hours of therapy are lacking. To address this, total and unoccupied high-affinity IgE receptor (Fc\u03b5RI) numbers per basophil, soluble Fc\u03b5RI (sFc\u03b5RI) and serum tryptase levels were measured before and after the first day of VIT induction in HVA patients. Additionally, basophil activation tests (BATs) were performed at those time points. In the early phase of VIT induction, no significant change in total Fc\u03b5RI receptor density on basophils was observed, but a significant increase in unoccupied Fc\u03b5RI was noticeable, predominantly in patients with high total IgE and low baseline unoccupied Fc\u03b5RI density. No meaningful difference in serum tryptase levels or sFc\u03b5RI levels was observed after VIT induction. BATs showed heterogeneous results, often unchanged before and after VIT (in 47% of the cases), sometimes increased (in 40%) and only rarely decreased EC50 sensitivity (in 13%). Changes in the BAT EC50 correlated with Fc\u03b5RI receptor density changes in basophils. In summary, VIT induction led to an increased ratio of unoccupied-to-total Fc\u03b5RI without notable tryptase or sFc\u03b5RI serum elevation, pointing towards subthreshold cell activation with receptor internalization and recycling. However, the mostly unchanged or even increased basophil sensitivity in EC50 calls for further research to clarify the clinical relevance of these rapid receptor modulations.<\/jats:p>","DOI":"10.3390\/ijms26157511","type":"journal-article","created":{"date-parts":[[2025,8,6]],"date-time":"2025-08-06T07:45:11Z","timestamp":1754466311000},"page":"7511","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Rapid Change in Fc\u03b5RI Occupancy on Basophils After Venom Immunotherapy Induction"],"prefix":"10.3390","volume":"26","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-0090-8866","authenticated-orcid":false,"given":"Viktoria","family":"Puxkandl","sequence":"first","affiliation":[{"name":"Department for Dermatology and Venerology, Kepler University Hospital, 4020 Linz, Austria"},{"name":"Center for Medical Research (ZMF), Johannes Kepler University, 4020 Linz, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0003-1285-1662","authenticated-orcid":false,"given":"Stefan","family":"Aigner","sequence":"additional","affiliation":[{"name":"Department for Dermatology and Venerology, Kepler University Hospital, 4020 Linz, Austria"},{"name":"Center for Medical Research (ZMF), Johannes Kepler University, 4020 Linz, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Teresa","family":"Burner","sequence":"additional","affiliation":[{"name":"Department for Dermatology and Venerology, Kepler University Hospital, 4020 Linz, Austria"},{"name":"Center for Medical Research (ZMF), Johannes Kepler University, 4020 Linz, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Angelika","family":"Lackner","sequence":"additional","affiliation":[{"name":"Department for Dermatology and Venerology, Kepler University Hospital, 4020 Linz, Austria"},{"name":"Center for Medical Research (ZMF), Johannes Kepler University, 4020 Linz, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3775-2989","authenticated-orcid":false,"given":"Sherezade","family":"Mo\u00f1ino-Romero","sequence":"additional","affiliation":[{"name":"Institute of Allergology, Charit\u00e9-Universit\u00e4tsmedizin Berlin, Corporate Member of Freie Universit\u00e4t Berlin, Humboldt-Universit\u00e4t zu Berlin, 10117 Berlin, Germany"},{"name":"Fraunhofer Institute for Translational Medicine and Pharmacology (ITMP), Immunology and Allergology (IA), 12203 Berlin, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Susanne","family":"Kimeswenger","sequence":"additional","affiliation":[{"name":"Department for Dermatology and Venerology, Kepler University Hospital, 4020 Linz, Austria"},{"name":"Center for Medical Research (ZMF), Johannes Kepler University, 4020 Linz, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Wolfram","family":"Hoetzenecker","sequence":"additional","affiliation":[{"name":"Department for Dermatology and Venerology, Kepler University Hospital, 4020 Linz, Austria"},{"name":"Center for Medical Research (ZMF), Johannes Kepler University, 4020 Linz, Austria"},{"name":"Clinical Research Institute for Inflammation Medicine, Medical Faculty, Johannes Kepler University, 4020 Linz, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9955-385X","authenticated-orcid":false,"given":"Sabine","family":"Altrichter","sequence":"additional","affiliation":[{"name":"Department for Dermatology and Venerology, Kepler University Hospital, 4020 Linz, Austria"},{"name":"Center for Medical Research (ZMF), Johannes Kepler University, 4020 Linz, Austria"},{"name":"Institute of Allergology, Charit\u00e9-Universit\u00e4tsmedizin Berlin, Corporate Member of Freie Universit\u00e4t Berlin, Humboldt-Universit\u00e4t zu Berlin, 10117 Berlin, Germany"},{"name":"Fraunhofer Institute for Translational Medicine and Pharmacology (ITMP), Immunology and Allergology (IA), 12203 Berlin, Germany"},{"name":"Clinical Research Institute for Inflammation Medicine, Medical Faculty, Johannes Kepler University, 4020 Linz, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,8,4]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"529","DOI":"10.1016\/0091-6749(92)90319-W","article-title":"Immunotherapy with honeybee venom and yellow jacket venom is different regarding efficacy and safety","volume":"89","author":"Helbling","year":"1992","journal-title":"J. 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