IL6 and myeloid sarcoma: Initially identified in 1997 as a retrovirus detected in multiple sclerosis (MS) patients, multiple sclerosis-associated retroviral element (MSRV) was eventually acknowledged as an endogenous retrovirus belonging to the HERV-W family and its expression was shown to correlate with the inflammatory cytokines IL-6 and IL12p40 in MS patients [96,97].