B lymphocytes from MS patients display abnormal and exaggerated PIC responses, including an elevated ratio of lymphotoxin (LT) to interleukin (IL)-10, and enhanced secretion of LT and tumour necrosis factor alpha (TNFα) when activated by INF-γ or via toll-like receptor 9 (TLR9) engagement induced by the pathogen-associated molecular pattern (PAMP) ligand CpG-DNA [117]. The gene discussed is TLR9; the disease is myeloid sarcoma.