Fluge, Øystein, Mella, Olav · BMC neurology · 2009 · DOI
This study examined whether a drug called rituximab, which reduces B cells (a type of immune cell), could help ME/CFS patients. Three ME/CFS patients received rituximab infusions and all experienced significant symptom improvement lasting several months. When symptoms returned, patients were retreated and improved again, suggesting that B cells may play a role in ME/CFS for at least some patients.
This study was the first to systematically test whether reducing B cells could improve ME/CFS symptoms, providing preliminary evidence that immune dysfunction—specifically B-cell dysfunction—may contribute to ME/CFS in some patients. This finding opened new avenues for understanding the biological basis of ME/CFS and for developing targeted immunotherapies, shifting the field toward investigating specific immune mechanisms rather than treating ME/CFS as purely psychiatric.
This case series does not prove that B-cell depletion cures ME/CFS or that it works for all patients—only three patients were treated, and symptoms eventually returned in all cases. It does not establish causation (that B cells cause ME/CFS) or identify which ME/CFS patients would benefit; broader controlled trials are needed to determine efficacy, optimal dosing, patient selection, and long-term safety. The delayed response (weeks 6–26) and variable relapse timelines also suggest the mechanism is complex and not yet understood.
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
Fluge, Øystein & Mella, Olav (2009). Clinical impact of B-cell depletion with the anti-CD20 antibody rituximab in chronic fatigue syndrome: a preliminary case series.. BMC neurology. https://doi.org/10.1186/1471-2377-9-28
BibTeX
@article{mecfsatlas-fluge-2009-clinical-impact,
author = {Fluge, Øystein and Mella, Olav},
title = {Clinical impact of B-cell depletion with the anti-CD20 antibody rituximab in chronic fatigue syndrome: a preliminary case series.},
journal = {BMC neurology},
year = {2009},
doi = {10.1186/1471-2377-9-28},
note = {PubMed: 19566965},
url = {https://www.mecfsatlas.com/evidence/fluge-2009-clinical-impact},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-26. https://www.mecfsatlas.com/evidence/fluge-2009-clinical-impact
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