{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,11,4]],"date-time":"2026-11-04T17:23:05Z","timestamp":1793812985144,"version":"4.6.1"},"reference-count":34,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2025,5,30]],"date-time":"2025-05-30T00:00:00Z","timestamp":1748563200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Immunol."],"abstract":"<jats:sec><jats:title>Background<\/jats:title><jats:p>Persistent symptoms following SARS-CoV-2 is an increasing problem after COVID-19 disease. The pathogenesis of this persistent post Covid-19 Condition (PCC) is, however, largely unknown. We hypothesized that persistent T cell activation and exhaustion play a role in PCC development.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>We examined plasma levels of soluble (s) CD25, TIM-3 and LAG-3, all markers of T cell activation\/exhaustion, by enzyme immunoassays in 170 home-isolated and 53 hospitalized patients for up to 18 months after COVID-19 in relation to persistent symptomatology.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>Our major findings were: (i) Cases with persistent dyspnea and fatigue had markedly higher sCD25 at 6\u201318 months with a more modest increase in sTIM-3. (ii) Cases with memory problems at 12\u201318 months had increased sLAG-3 iii) sCD25 correlated with SARS-CoV-2 antibody titers and microneutralization titers only in cases with PCC while sTIM-3 correlated with these parameters irrespectively of symptoms. iv) Although hospitalized patients had markedly elevated levels of T cell activation\/exhausting markers during follow-up, there was no relation to PCC symptoms.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusion<\/jats:title><jats:p>Our study indicates a role for T cell activation\/exhaustion in PCC following home isolated COVID-19 infection, with somewhat different patterns of sCD25, sTIM-3 and sLAG-3, but not in hospitalized COVID-19 patients where disease severity may be more important.<\/jats:p><\/jats:sec>","DOI":"10.3389\/fimmu.2025.1578208","type":"journal-article","created":{"date-parts":[[2025,5,30]],"date-time":"2025-05-30T05:46:22Z","timestamp":1748583982000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":4,"title":["Markers of T cell activation and exhaustion in plasma are associated with persistent symptoms up to 18 months following mild SARS-CoV-2 infection"],"prefix":"10.3389","volume":"16","author":[{"given":"Thor","family":"Ueland","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Rebecca Jane","family":"Cox","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Annika E.","family":"Michelsen","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Elisabeth Berg","family":"Fjelltveit","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kari","family":"Otterdal","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tuva","family":"Dahl","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Fan","family":"Zhou","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Rebecca","family":"Elyanow","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"P\u00e5l","family":"Aukrust","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Bj\u00f8rn","family":"Blomberg","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Bente E.","family":"Halvorsen","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nina","family":"Langeland","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2025,5,30]]},"reference":[{"key":"B1","unstructured":"WHO Coronavirus (COVID-19) dashboard\n          \n          \n          \n          2023"},{"key":"B2","doi-asserted-by":"publisher","DOI":"10.1093\/infdis\/jiac136","article-title":"Global prevalence of post-coronavirus disease 2019 (COVID-19) condition or long COVID: A meta-analysis and systematic review","volume":"226","author":"Chen","year":"2022","journal-title":"J Infect Dis"},{"key":"B3","doi-asserted-by":"publisher","DOI":"10.1016\/S2215-0366(21)00084-5","article-title":"6-month neurological and psychiatric outcomes in 236\u2009379 survivors of COVID-19: a retrospective cohort study using electronic health records","volume":"8","author":"Taquet","year":"2021","journal-title":"Lancet Psychiatry"},{"key":"B4","doi-asserted-by":"publisher","first-page":"10458","DOI":"10.3390\/ijms241310458","article-title":"Laboratory findings and biomarkers in long COVID: what do we know so far? 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