IDO1 and Alzheimer disease: As a follow-up to a recent publication from our group [22], where higher proportions of PD-1+ cells and a tendency for lower proportions of PD-L1+ and Epstein–Barr virus (EBV) positive cells in benign lymphadenopathies from patients with AD were found, the aim of this study was to investigate IDO1 and PD-L2 in the same material.