The presence of T lymphocytes in the healthy human brain has been recently reported unchanged across age69 and to similar cortical levels as in patients with various neurological disorders when compared with old controls.20,70 Of note, CD8+ T cells were largely predominant versus CD4+ T cells,20,70 with most of the lymphocytes in the perivascular spaces,69 as in our study. The gene discussed is CD4; the disease is nervous system disorder.