TNF and myeloid sarcoma: Numerous pro-inflammatory cytokines (e.g., interferon-gamma (IFN-γ) and tumour necrosis factor-alpha (TNF-α), IL-1β, IL-17) are elevated in MS lesions and cerebrospinal fluid (CSF) and can induce the kynurenine pathway (KP) of tryptophan metabolism in immune and glial cells.