IL1B and myeloid sarcoma: The combination of IL-1β or IL-1ra mRNA in situ hybridization histochemistry with immunohistochemistry for CD68 indicated that infiltrating macrophages and/or activated endogenous microglial cells in WM and GM are the main sources of IL-1β and IL-1ra mRNA production during conditions of cr-EAE, which is in line with research showing increased expression of IL-1β in activated microglia and macrophages in EAE [41], [62], [63] and in MS [38].