ORIGINAL RESEARCH article
Front. Immunol.
Sec. Cytokines and Soluble Mediators in Immunity
This article is part of the Research TopicCytokine Interactions and Biomarker Potential in Various DiseasesView all 15 articles
Principal Component Analysis of Cytokine Signature in COVID-19 and Long COVID
Provisionally accepted
- 1Laboratory of Molecular Immunology, Saint Petersburg Pasteur Institute, Saint Petersburg, Russia
- 2Department of Immunology, Pervyj Sankt-Peterburgskij gosudarstvennyj medicinskij universitet imeni akademika I P Pavlova, Saint Petersburg, Russia
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Despite the activity of the COVID-19 pandemic being lower in the recent years, new COVID-associated threat, known long COVID (LC), has emerged. Its clinical presentation includes nearly 200 symptoms affecting cardiovascular, respiratory, nervous systems, endocrine organs, urinary tract, and gastrointestinal systems. Cytokines serve as important biomarkers for assessing the level of immune system involvement and dysregulation in LC. Most studies on cytokine network and cytokine interactions usually address more traditional methods of statistical analysis with comparison criteria, discriminant analysis, regression. But multiplex cytokine analysis includes dozens of parameters, and requires complex assessment of the network as a whole. . We analyzed data of cytokine multiplex analysis of 289 patients with COVID-19, 44 patients with LC and 51 healthy donors. Using principal component analysis (PCA) we identified cyotkines with the highest importance rate, and further investigated relationship between them with the use of 3D mapping. As a result, three key clusters were identified: cluster A - IL-13, CCL7/MCP-3, IL-4; cluster B - IL-18, CCL2/MCP-1, CCL4/MIP-1β, CXCL8/IL-8, M-CSF, and cluster C - sCD40L, CXCL1/GROα, PDGF-AA, EGF, FGF-2, FLT-3L, IL-7, IL-17F. The coordinated interactions within these clusters reveal a complex immunopathology behind LC, but leave an opening for further interpretation.
Keywords: Long Covid, Post COVID condition, COVID-19, Cytokines, Principal componentanalysis, Clusterization, cytokine network
Received: 01 Oct 2025; Accepted: 12 Feb 2026.
Copyright: © 2026 Korobova and Totolian. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Zoia R. Korobova
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