PDCD1 and Alzheimer disease: Most reported studies have evaluated classical regulatory T cell subsets (Table 1) in the context of AHSCT for AD, but Zhang et al. (26) identified peripheral CD8+ T cells from SLE patients with sustained high FoxP3 expression and increased expression of CTLA-4, PD-1, PD-L1, latency-associated peptide (LAP), and CD103, when compared with pre-transplant CD8+ T cells.