{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,17]],"date-time":"2026-04-17T14:36:07Z","timestamp":1776436567021,"version":"3.51.2"},"reference-count":49,"publisher":"MDPI AG","issue":"23","license":[{"start":{"date-parts":[[2022,12,1]],"date-time":"2022-12-01T00:00:00Z","timestamp":1669852800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJMS"],"abstract":"<jats:p>Appendicitis is the most common abdominal surgical emergency, but its aetiology is not fully understood. We and others have proposed that allergic responses play significant roles in its pathophysiology. Eosinophils and Interleukin (IL)-5 are involved in a hypersensitivity type I reaction. Eosinophil infiltration is common in the allergic target organ and is dependent on IL-5. In the presence of an allergic component, it is expected that the eosinophil count and IL-5 local and systemic concentrations become elevated. To address this hypothesis, we designed a prospective study that included 65 patients with acute appendicitis (grouped as acute phlegmonous or gangrenous according to the histological definition) and 18 patients with the clinical diagnosis of acute appendicitis, but with normal histological findings (control group) were enrolled. Eosinophil blood counts and appendicular wall eosinophil infiltration were determined. IL-5 levels in blood and appendicular lavage fluid were evaluated. Appendicular lavage fluid was collected by a new methodology developed and standardized by our group. Appendicular wall eosinophil infiltration was higher in acute phlegmonous appendicitis than in gangrenous appendicitis (p = 0.000). IL-5 blood levels were similar in both pathologic and control groups (p &gt; 0.05). In the appendicular lavage fluid, the higher levels of IL-5 were observed in the phlegmonous appendicitis group (p = 0.056). We found a positive correlation between the appendicular wall eosinophilic infiltration and the IL-5 concentrations, in both the blood and the appendicular lavage fluid, supporting the IL-5 reliance in eosinophil local infiltration. We observed the highest presence of eosinophils at phlegmonous appendicitis walls. In conclusion, the present data are compatible with a hypersensitivity type I allergic reaction in the target organ, the appendix, during the phlegmonous phase of appendicitis.<\/jats:p>","DOI":"10.3390\/ijms232315086","type":"journal-article","created":{"date-parts":[[2022,12,1]],"date-time":"2022-12-01T04:28:57Z","timestamp":1669868937000},"page":"15086","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":17,"title":["IL-5 Serum and Appendicular Lavage Fluid Concentrations Correlate with Eosinophilic Infiltration in the Appendicular Wall Supporting a Role for a Hypersensitivity Type I Reaction in Acute Appendicitis"],"prefix":"10.3390","volume":"23","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-9325-0145","authenticated-orcid":false,"given":"Nuno","family":"Carvalho","sequence":"first","affiliation":[{"name":"Servi\u00e7o Cirurgia Geral, Hospital Garcia de Orta, 2805-267 Almada, Portugal"},{"name":"Faculdade Medicina, Universidade Lisboa, 1649-028 Lisboa, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4165-7052","authenticated-orcid":false,"given":"Elisabete","family":"Carolino","sequence":"additional","affiliation":[{"name":"H&TRC-Health & Technology Research Center, ESTeSL-Escola Superior de Tecnologia da Sa\u00fade, Instituto Polit\u00e9cnico de Lisboa, 1990-096 Lisboa, Portugal"}]},{"given":"H\u00e9lder","family":"Coelho","sequence":"additional","affiliation":[{"name":"Servi\u00e7o de Anatomia Patol\u00f3gica, Hospital Garcia de Orta, 2805-267 Almada, Portugal"}]},{"given":"Ana","family":"C\u00f3ias","sequence":"additional","affiliation":[{"name":"Servi\u00e7o de Anatomia Patol\u00f3gica, Hospital Garcia de Orta, 2805-267 Almada, Portugal"}]},{"given":"Madalena","family":"Trindade","sequence":"additional","affiliation":[{"name":"Servi\u00e7o Cirurgia Geral, Hospital Garcia de Orta, 2805-267 Almada, Portugal"}]},{"given":"Jo\u00e3o","family":"Vaz","sequence":"additional","affiliation":[{"name":"Servi\u00e7o Cirurgia Geral, Hospital Garcia de Orta, 2805-267 Almada, Portugal"}]},{"given":"Brigitta","family":"Cismasiu","sequence":"additional","affiliation":[{"name":"Servi\u00e7o Cirurgia Geral, Hospital Garcia de Orta, 2805-267 Almada, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9910-2343","authenticated-orcid":false,"given":"Catarina","family":"Moita","sequence":"additional","affiliation":[{"name":"Innate Immunity and Inflammation Lab, Instituto Gulbenkian de Ci\u00eancia, 2780-156 Oeiras, Portugal"}]},{"given":"Luis","family":"Moita","sequence":"additional","affiliation":[{"name":"Innate Immunity and Inflammation Lab, Instituto Gulbenkian de Ci\u00eancia, 2780-156 Oeiras, Portugal"},{"name":"Instituto de Histologia e Biologia do Desenvolvimento, Faculdade Medicina, Universidade Lisboa, 1649-028 Lisboa, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7550-8285","authenticated-orcid":false,"given":"Paulo Matos","family":"Costa","sequence":"additional","affiliation":[{"name":"Servi\u00e7o Cirurgia Geral, Hospital Garcia de Orta, 2805-267 Almada, Portugal"},{"name":"Faculdade Medicina, Universidade Lisboa, 1649-028 Lisboa, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2022,12,1]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1155\/2021\/8848162","article-title":"Appendicectomy for Uncomplicated Simple Appendicitis: Is It Always Required?","volume":"2021","author":"Alsubsiee","year":"2021","journal-title":"Surg. 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