CD4 and Alzheimer disease: We have previously reported that soluble mediators in the sera of patients with liver disease can induce phenotypic and functional properties resembling those detected ex vivo in circulating leucocytes from patients.15 34 As shown in figure 4A, in vitro exposure of healthy CD4+ T cells to sera from patients with AD resulted in enhancement of HLA-G surface expression; no such elevation was observed after exposure to sera from HCs or a pathological control (online supplemental figure S5A).