TNF and myalgic encephalomeyelitis/chronic fatigue syndrome: Although some biomarkers, including antibodies against β-adrenergic receptors and muscarinic acetylcholine receptors, oxidative stress and anti-oxidative activity, and inflammatory cytokines, such as interleukin-1β, tumor necrosis factor-α, and nuclear factor-kappa B, have been studied, none of them has sufficient reliability for clinical use in the diagnosis or severity evaluation of ME/CFS [14,38,39].