CD27 and amyotrophic lateral sclerosis: In ALS, an initial, circumscribed and protective response (M2) is thought to be followed by a more extended and sustained pro-inflammatory reaction (M1), both in areas of neurodegeneration and systemically.1 In support of this hypothesis, we have recently shown increased frequencies of senescent CD4+CD27-CD57+ T cells, memory CD8+ T and late memory B cells, in blood from people living with ALS (pwALS).