In line with findings showing an increase in proinflammatory Th1 cells in the CSF of ALS [29] and MS patients [69], we showed that the majority of CD4 T cells in the SC of SOD1G37R mice exhibited a Th1 phenotype and expressed the activation markers CD69, CD81 and the checkpoint molecule PD1 as part of their effector function within the CNS. Here, CD81 is linked to myeloid sarcoma.