The search string used was as follows: (“Microglia” OR “astrocytes” OR “T lymphocytes” OR “B lymphocytes” OR “NK cells” OR “CD4+ T cells” OR “CD8+ T cells” OR “Th17 cells” OR “Th1 cells” OR “Treg cells”) AND (“neurodegenerative diseases” OR “Parkinson’s disease” OR “Alzheimer’s disease” OR “amyotrophic lateral sclerosis” OR “multiple sclerosis” OR “neuroinflammation”). Here, CD4 is linked to amyotrophic lateral sclerosis.