We have demonstrated in mouse models of amyotrophic lateral sclerosis (ALS) and Alzheimer’s disease (AD) that Eomes+ Th cells infiltrate into the CNS during neurodegenerative disease where they secrete neurotoxic granzyme B after encountering ectopically expressed ORF1 antigen encoded by L1 retrotransposon [25]. The gene discussed is EOMES; the disease is Alzheimer disease.