MOG and myeloid sarcoma: Despite constituting only ∼0.05% of the total myelin protein (Johns and Bernard 1999), MOG is a highly significant B cell autoantigen in MS, with antibodies against MOG contributing to myelin destruction (Schluesener et al. 1987; Linington et al. 1988; Litzenburger et al. 1998; Storch et al. 1998).