E2 ModeratePreliminaryPEM unclearCross-SectionalPeer-reviewedReviewed
Extended B cell phenotype in patients with myalgic encephalomyelitis/chronic fatigue syndrome: a cross-sectional study.
Mensah, F, Bansal, A, Berkovitz, S et al. · Clinical and experimental immunology · 2016 · DOI
Quick Summary
Researchers compared immune cells called B cells in people with ME/CFS and healthy people using specialized lab tests. While they didn't find major differences in the most common B cell types, they did discover subtle changes in how B cells are marked and organized in ME/CFS patients, particularly an increase in certain markers on specific B cell subsets. These findings suggest B cells may function differently in ME/CFS and could help explain why some patients improve with a drug that targets B cells.
Why It Matters
This study provides immunological evidence supporting the role of B cells in ME/CFS pathogenesis, particularly relevant given recent clinical trials showing symptom improvement with rituximab (B cell depletion therapy). These novel phenotypic markers may help identify which patients are most likely to respond to B cell-targeted treatments and could guide future therapeutic strategies.
Observed Findings
- Increased frequency and mean fluorescence intensity (MFI) of CD24 on total B cells, specifically within IgD+ subsets (P<0.01 for frequency; P=0.03 for MFI)
- Higher frequency of CD21+ CD38- B cells (>20%) in ME/CFS patients compared to healthy controls
- Negative correlation between CD21+ CD38- B cell frequency and disease duration in ME/CFS patients
- No differences in classical B cell subset percentages (defined by IgD, CD27, CD38) between ME/CFS patients and healthy controls
Inferred Conclusions
- B cell phenotypic alterations in ME/CFS may reflect subtle changes in B cell differentiation and function not captured by traditional subset classification
- These altered B cell phenotypes could represent the biological mechanism underlying clinical response to rituximab therapy in some ME/CFS patients
- If validated in other cohorts, these markers could serve as biological stratifiers for patient selection in rituximab trials and other B cell-targeted therapies
Remaining Questions
- Do these B cell phenotypic changes persist longitudinally, or do they fluctuate with disease activity and symptom severity?
- What is the functional significance of altered CD24 expression and CD21+ CD38- frequency—do these cells produce different antibodies or cytokines compared to healthy controls?
What This Study Does Not Prove
This study does not establish that these B cell changes cause ME/CFS symptoms or prove that B cell dysfunction is the primary driver of disease. The cross-sectional design cannot establish temporal relationships or whether these changes persist over time. The findings represent associations in a single cohort and require replication in other patient populations before clinical application.
Tags
Symptom:Post-Exertional MalaiseCognitive DysfunctionFatigue
Biomarker:Blood Biomarker
Method Flag:Small SampleExploratory OnlyStrong PhenotypingWeak Case Definition
Metadata
- DOI
- 10.1111/cei.12749
- PMID
- 26646713
- Review status
- Editor reviewed
- Evidence level
- Single-study or moderate support from human research
- Last updated
- 12 April 2026
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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