Comparable Immune Alterations and Inflammatory Signatures in ME/CFS and Long COVID.

Observed Findings

• Both ME/CFS and Long COVID groups showed significantly reduced total lymphocyte counts (ME/CFS: 2.472 × 10⁹/L; Long COVID: 2.051 × 10⁹/L) compared to healthy controls
• CD8+ T cell counts were substantially lower in both patient groups (ME/CFS: 0.394 × 10⁹/L; Long COVID: 0.404 × 10⁹/L) versus controls
• Natural killer (NK) cell counts were significantly reduced in both conditions (ME/CFS: 0.205 × 10⁹/L; Long COVID: 0.180 × 10⁹/L)
• Proinflammatory cytokines were elevated in both groups, including IL-6, TNF-α, IL-4, and IL-10
• No statistically significant differences in immune biomarkers were detected between ME/CFS and Long COVID patient groups

Inferred Conclusions

• ME/CFS and Long COVID display comparable immune and inflammatory profiles despite different etiopathogenic triggers, suggesting shared immunopathological mechanisms
• Both conditions are characterized by a specific pattern of immune dysregulation: reduced adaptive immunity (low T cells and NK cells) combined with heightened inflammatory cytokine production
• The immunological similarity between ME/CFS and Long COVID may justify unified clinical and research approaches to understanding these conditions
• These objective immune biomarker differences support the biological validity of both conditions as organic illnesses

Remaining Questions