{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,22]],"date-time":"2026-08-22T16:29:27Z","timestamp":1787416167491,"version":"build-2736575974"},"reference-count":32,"publisher":"Public Library of Science (PLoS)","issue":"5","license":[{"start":{"date-parts":[[2025,5,2]],"date-time":"2025-05-02T00:00:00Z","timestamp":1746144000000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"The Scientific and Technological Research Council of T\u00fcrkiye","award":["323S031"],"award-info":[{"award-number":["323S031"]}]},{"name":"The Presidency of Strategy and Budget of T\u00fcrkiye","award":["220K12-153120"],"award-info":[{"award-number":["220K12-153120"]}]}],"content-domain":{"domain":["www.plosone.org"],"crossmark-restriction":false},"short-container-title":["PLoS One"],"abstract":"<jats:p>Interleukin 40 (IL-40) is a novel cytokine that has been associated with B lymphocytes, particularly IgA-secreting cells in gut mucosa. Considering mucosal association of IL-40, we aimed to determine serum IL-40 levels in patients with Covid-19. We compared IL-40 concentrations in healthy people to both patients with mild symptoms of SARS-CoV-2 infection and pneumonia. IL-40 was measured by ELISA. Serum IgA levels were tested by nephelometry. For the first time, we demonstrated that SARS-CoV-2 infection increased serum IL-40 levels significantly. The elevation of IL-40 in serum was related to severity of the infection. Therefore, IL-40 concentrations were quite higher in patients with symptoms of pneumonia. Our findings indicated that IgA and NETosis biomarkers were related with IL-40 increase. Based on these findings, we speculated that IL-40 would be associated with immune activities in the mucosa of the lungs of SARS-CoV-2-infected patients. This association may be linked to a mechanism that has a control on IgA and NETosis.<\/jats:p>","DOI":"10.1371\/journal.pone.0321578","type":"journal-article","created":{"date-parts":[[2025,5,2]],"date-time":"2025-05-02T13:23:46Z","timestamp":1746192226000},"page":"e0321578","update-policy":"https:\/\/doi.org\/10.1371\/journal.pone.corrections_policy","source":"Crossref","is-referenced-by-count":5,"title":["Increased serum levels of IL-40 are associated with IgA and NETosis biomarkers in Covid-19 patients: IL-40 and infectious 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