AUTHOR=Ueland Thor , Cox Rebecca Jane , Michelsen Annika E. , Fjelltveit Elisabeth Berg , Otterdal Kari , Dahl Tuva , Zhou Fan , Elyanow Rebecca , Aukrust Pål , Blomberg Bjørn , Halvorsen Bente E. , Langeland Nina 

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

JOURNAL=Frontiers in Immunology

VOLUME=Volume 16 - 2025

YEAR=2025

URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2025.1578208

DOI=10.3389/fimmu.2025.1578208

ISSN=1664-3224

ABSTRACT=BackgroundPersistent 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.MethodsWe 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.ResultsOur major findings were: (i) Cases with persistent dyspnea and fatigue had markedly higher sCD25 at 6–18 months with a more modest increase in sTIM-3. (ii) Cases with memory problems at 12–18 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.ConclusionOur 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.