Peppercorn, Katie, Edgar, Christina D, Kleffmann, Torsten et al. · Scientific reports · 2023 · DOI
This small pilot study looked at immune cells from long COVID patients and compared them to healthy people, analyzing thousands of proteins in their blood. They found that long COVID patients had significant differences in their immune cell proteins, particularly in how their bodies handle energy production and immune function—similar patterns to what researchers have seen in ME/CFS. This suggests that long COVID and ME/CFS may share similar underlying biological problems, even though they start from different triggers.
This research provides molecular evidence that long COVID and ME/CFS share similar immune and mitochondrial dysfunction pathways, which could help explain why these conditions present with similar symptoms and may inform shared treatment approaches. Understanding these biological commonalities is crucial for validating ME/CFS pathophysiology and improving diagnosis and management strategies for both conditions.
This pilot study does not prove that long COVID and ME/CFS are the same disease, nor does it establish causation between the observed protein changes and symptoms. The small sample size (6 long COVID patients) limits the ability to draw definitive conclusions or account for heterogeneity within each condition. The study provides suggestive evidence of mechanistic overlap but requires larger, prospective validation studies.
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
The first block is for the primary paper and is the citation you should use in research work. The atlas-snapshot line only applies if you are specifically referring to this atlas’s reading of the paper on the date shown.
Primary citation
Peppercorn, Katie, Edgar, Christina D, Kleffmann, Torsten, & Tate, Warren P (2023). A pilot study on the immune cell proteome of long COVID patients shows changes to physiological pathways similar to those in myalgic encephalomyelitis/chronic fatigue syndrome.. Scientific reports. https://doi.org/10.1038/s41598-023-49402-9
BibTeX
@article{mecfsatlas-peppercorn-2023-pilot-study,
author = {Peppercorn, Katie and Edgar, Christina D and Kleffmann, Torsten and Tate, Warren P},
title = {A pilot study on the immune cell proteome of long COVID patients shows changes to physiological pathways similar to those in myalgic encephalomyelitis/chronic fatigue syndrome.},
journal = {Scientific reports},
year = {2023},
doi = {10.1038/s41598-023-49402-9},
note = {PubMed: 38086949},
url = {https://www.mecfsatlas.com/evidence/peppercorn-2023-pilot-study},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-30. https://www.mecfsatlas.com/evidence/peppercorn-2023-pilot-study
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