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

Background

Chronic Fatigue Syndrome (CFS), also known as Myalgic Encephalomyelitis (ME), is a debilitating condition characterized by persistent fatigue and multisystemic symptoms, such as cognitive impairment, musculoskeletal pain, and post-exertional malaise. Recently, parallels have been drawn between ME/CFS and Long COVID, a post-viral syndrome following infection with SARS-CoV-2, which shares many clinical features with CFS. Both conditions involve chronic immune activation, raising questions about their immunopathological overlap.

Objectives

This study aimed to compare immune biomarkers between patients with ME/CFS or Long COVID and healthy controls to explore shared immune dysfunction.

Methods

We analyzed lymphocyte subsets, cytokine profiles, psychological status and their correlations in 190 participants, 65 with CFS, 54 with Long COVID, and 70 healthy controls.

Results

When compared to healthy subjects, results in both conditions were marked by lower levels of lymphocytes (CFS-2.472 × 109/L, p = 0.006, LC-2.051 × 109/L, p = 0.009), CD8+ T cells (CFS-0.394 × 109/L, p = 0.001, LC-0.404 × 109/L, p = 0.001), and NK cells (CFS-0.205 × 109/L, p = 0.001, LC-0.180 × 109/L, p = 0.001), and higher levels of proinflammatory cytokines such as IL-6 (CFS-3.35 pg/mL, p = 0.050 LC-4.04 pg/mL, p = 0.001), TNF (CFS-2.64 pg/mL, p = 0.023, LC-2.50 pg/mL, p = 0.025), IL-4 (CFS-3.72 pg/mL, p = 0.041, LC-3.45 pg/mL, p = 0.048), and IL-10 (CFS-2.29 pg/mL, p = 0.039, LC-2.25 pg/mL, p = 0.018).

Conclusions

Notably, there were no significant differences between CFS and Long COVID patients in the tested biomarkers. These results demonstrate that ME/CFS and Long COVID display comparable immune and inflammatory profiles, with no significant biomarker differences observed between the two groups.