CD4 and amyotrophic lateral sclerosis: Accordingly, CD4+ CD25+ regulatory T cells (Tregs) and CD4+ T helper (Th)2 cells tend to mediate a neuroprotective effect, whereas the presence of CD4+ Th1, CD4+ Th17, cytotoxic CD8+, and Natural killer (NK) cells, and effector T lymphocytes (Teffs), is associated with a more rapid progression of ALS and an increased risk of death [22,23].