TNF and myalgic encephalomeyelitis/chronic fatigue syndrome: The activin B response was unique as in addition to activin A, the levels of the other cytokines measured, namely IL-2, IL-4, IL-6, IL-10, IL-17A, TNFα and IFN-γ, were not statistically significant between groups (Table 1: IL-17A was detected in 2/45 CFS/ME samples and no controls, while serum TNFα was detected in 3/45 CFS/ME samples and no controls).