TLR3 and myeloid sarcoma: As demyelination involves innate immune activation, and as TLR3 and TLR4 are prominently present on reactive ASTRs in WM MS lesions [13, 49], we next examined whether gmASTRs and wmASTRs may respond differently to TLR3 and/or TLR4 agonists and as a consequence distinctly modulate OPC behavior.