CD4 and amyotrophic lateral sclerosis: Interestingly, we also observed reduced frequencies of CD4 CTLs (CD3+CD4+CCL5+EOMES+) and EM CD4 CTLs (CD3+CD4+CD44+CD62L−CCL5+EOMES+) (Fig. 1N–O), cells which were recently implicated in aging and ALS [29, 31].