Querec, Troy D, Abrams, Joseph, Stewart, Jennifer J et al. · Journal of immunological methods · 2021 · DOI
This study tested different laboratory methods for measuring natural killer (NK) cell function—an immune system measurement that may be important for ME/CFS—using blood samples that were shipped overnight instead of tested immediately. Researchers compared three different testing approaches and found that two of them (CRCA and FCCA) gave similar results when blood samples were processed a day after collection, suggesting these tests could work for clinical settings where samples need to be shipped.
NK cell dysfunction is a potential biomarker for ME/CFS, but research has been limited by the need to test samples immediately after collection. This study demonstrates that practical shipping and overnight storage protocols can maintain the validity of NK cell testing, which could enable standardized multi-site clinical trials and broader diagnostic implementation for ME/CFS patients.
This study does not establish that NK cell dysfunction causes ME/CFS or prove its diagnostic utility; it only addresses technical feasibility of measuring NK function under shipping conditions. The small sample size (31 participants) and limited generalizability (only three clinics) mean results may not apply across all laboratory settings. Correlation between assays does not confirm their clinical relevance for ME/CFS diagnosis or prognosis.
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 →
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Primary citation
Querec, Troy D, Abrams, Joseph, Stewart, Jennifer J, Barnes, Zachary, Balbin, Elizabeth, Klimas, Nancy, et al. (2021). Evaluation of natural killer cell assay performance on shipped blood specimens.. Journal of immunological methods. https://doi.org/10.1016/j.jim.2021.113049
BibTeX
@article{mecfsatlas-querec-2021-evaluation-natural,
author = {Querec, Troy D and Abrams, Joseph and Stewart, Jennifer J and Barnes, Zachary and Balbin, Elizabeth and Klimas, Nancy and Fletcher, Mary Ann and Brown, Lynette and Bertolli, Jeanne and Unger, Elizabeth R},
title = {Evaluation of natural killer cell assay performance on shipped blood specimens.},
journal = {Journal of immunological methods},
year = {2021},
doi = {10.1016/j.jim.2021.113049},
note = {PubMed: 33819446},
url = {https://www.mecfsatlas.com/evidence/querec-2021-evaluation-natural},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-28. https://www.mecfsatlas.com/evidence/querec-2021-evaluation-natural
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