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Complement activation in patients with post-acute sequelae after SARS-CoV-2 infection

Holmqvist, Madlene LU ; Sjöström, Dick J. ; Carlson, Katherine LU orcid ; Gullstrand, Birgitta LU ; Bengtsson, Anders A. LU ; Kahn, Robin LU ; Mollnes, Tom E. ; Åkesson, Per LU ; Nilsson, Per H. and Kahn, Fredrik LU (2026) In Frontiers in Immunology 17.
Abstract

Introduction – Post-acute sequelae of SARS-CoV-2 (PASC) may develop after SARS-CoV-2 infection and cause a wide range of symptoms that can persist for years. Several pathophysiological mechanisms have been proposed, including dysregulation of the complement system. Methods – In this study, we analysed markers of complement activation in a cohort of patients with PASC, up to 33 months after the initial infection. We measured the complement activation markers C3bc, C3bBbP and TCC in 38 PASC patients with an initial mild COVID-19 infection, 10 PASC patients with an initial severe COVID-19 infection and 80 control subjects who had recovered completely after a COVID-19 infection. Results – Although the patients with an acute mild SARS-CoV-2... (More)

Introduction – Post-acute sequelae of SARS-CoV-2 (PASC) may develop after SARS-CoV-2 infection and cause a wide range of symptoms that can persist for years. Several pathophysiological mechanisms have been proposed, including dysregulation of the complement system. Methods – In this study, we analysed markers of complement activation in a cohort of patients with PASC, up to 33 months after the initial infection. We measured the complement activation markers C3bc, C3bBbP and TCC in 38 PASC patients with an initial mild COVID-19 infection, 10 PASC patients with an initial severe COVID-19 infection and 80 control subjects who had recovered completely after a COVID-19 infection. Results – Although the patients with an acute mild SARS-CoV-2 infection had a trend towards more severe PASC, we could not find any significant differences in complement activation markers between these patients and controls. Conclusion – We could not find convincing evidence of activation of the complement system in PASC patients.

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; ; ; ; ; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
complement activation, COVID-19, long COVID, PACS, PASC, post COVID syndrome, SARS-CoV-2
in
Frontiers in Immunology
volume
17
article number
1779393
publisher
Frontiers Media S. A.
external identifiers
  • pmid:42212121
  • scopus:105040598889
ISSN
1664-3224
DOI
10.3389/fimmu.2026.1779393
language
English
LU publication?
yes
additional info
Publisher Copyright: Copyright © 2026 Holmqvist, Sjöström, Carlson, Gullstrand, Bengtsson, Kahn, Mollnes, Åkesson, Nilsson and Kahn.
id
aac3197b-35fc-445a-900c-aa438a8ce7be
date added to LUP
2026-07-23 13:20:40
date last changed
2026-08-20 15:37:00
@article{aac3197b-35fc-445a-900c-aa438a8ce7be,
  abstract     = {{<p>Introduction – Post-acute sequelae of SARS-CoV-2 (PASC) may develop after SARS-CoV-2 infection and cause a wide range of symptoms that can persist for years. Several pathophysiological mechanisms have been proposed, including dysregulation of the complement system. Methods – In this study, we analysed markers of complement activation in a cohort of patients with PASC, up to 33 months after the initial infection. We measured the complement activation markers C3bc, C3bBbP and TCC in 38 PASC patients with an initial mild COVID-19 infection, 10 PASC patients with an initial severe COVID-19 infection and 80 control subjects who had recovered completely after a COVID-19 infection. Results – Although the patients with an acute mild SARS-CoV-2 infection had a trend towards more severe PASC, we could not find any significant differences in complement activation markers between these patients and controls. Conclusion – We could not find convincing evidence of activation of the complement system in PASC patients.</p>}},
  author       = {{Holmqvist, Madlene and Sjöström, Dick J. and Carlson, Katherine and Gullstrand, Birgitta and Bengtsson, Anders A. and Kahn, Robin and Mollnes, Tom E. and Åkesson, Per and Nilsson, Per H. and Kahn, Fredrik}},
  issn         = {{1664-3224}},
  keywords     = {{complement activation; COVID-19; long COVID; PACS; PASC; post COVID syndrome; SARS-CoV-2}},
  language     = {{eng}},
  month        = {{05}},
  publisher    = {{Frontiers Media S. A.}},
  series       = {{Frontiers in Immunology}},
  title        = {{Complement activation in patients with post-acute sequelae after SARS-CoV-2 infection}},
  url          = {{http://dx.doi.org/10.3389/fimmu.2026.1779393}},
  doi          = {{10.3389/fimmu.2026.1779393}},
  volume       = {{17}},
  year         = {{2026}},
}