LINGO1 and myeloid sarcoma: This potential dominant inhibitory effect of pro-inflammatory reactive astrocytes may explain why several drugs that induce OPC differentiation and myelination of axons in pre-clinical studies including clemastine, bexarotene, and anti-LINGO-1 have had underwhelming results in MS clinical trials (Cadavid et al., 2017; Green et al., 2017; Brown et al., 2021).