VTN and myeloid sarcoma: In progressive MS and long-standing disease patients, white matter plaques were consistently positive for complement proteins (C3, factor B, and C1q), regulators (factor H, C1inh, and clusterin) and activation products [C3b, iC3b, C4d, and terminal complement complex (TCC)] providing evidence that, once established, progression of inflammation in MS may not rely on infiltrating cells but rather on innate immune mechanisms including complement activation (31, 32).