In the CFS group, serum concentrations of TNF (2.64 pg/mL, 1.9–7.47), IL-10 (2.29 pg/mL, 2.05–3.01), IL-6 (3.35 pg/mL, 2.36–6.77), IL-4 (3.72 pg/mL, 2.45–5.57), and IL-2 (1.38 pg/mL, 1.30–2.65) were significantly elevated compared to HC (Figure 2), except for IL-17A (13.75 pg/mL, 10.19–36.51), which did not show any statistically significant difference between groups, and IFN-γ (2.55 pg/mL, 1.85–3.7), which was significantly lower compared to LC. Here, IL4 is linked to myalgic encephalomeyelitis/chronic fatigue syndrome.