CD4 and amyotrophic lateral sclerosis: We detected a significant difference in the expression of IFN-γ by CD4+ T cells in HCs compared to ALS patients after stimulation with HERV-K env 19–37 peptide (ALS vs. HCs mean ± SD = 0.023 ± 0.082 vs. 0.07 ± 0.03; p = 0.044) (Figure 3e).