With age, they can secrete inflammatory molecules such as tumour necrosis factor (TNF) and interleukin 6 (IL-6), produce autoantibodies (i.e. anti-DNA, not necessarily correlated to an autoimmune disease) and expand clones after chronic viral infections such as those by Epstein–Barr virus (EBV) or cytomegalovirus (CMV).21 In the pathogenesis of multiple sclerosis, such cells play a pivotal role and indeed several studies have demonstrated the presence of self-reacting, immunoglobulin-producing B cell clones in the CSF, meninges and brain. The gene discussed is IL6; the disease is autoimmune disease.