Notably, in AD patients T cell in peripheral blood and infiltrating the brain are indeed activated and display memory phenotype (Shalit et al., 1995; Lombardi et al., 1999, 2004; Tan et al., 2002b; Togo et al., 2002); levels of IL-6 in plasma (Singh and Guthikonda, 1997), augmented production of IFN-γ and TNF-α by natural killer (NK) cells (Solerte et al., 2000), and an increase in IL-1β associated with a concomitant decrease in IL-10 have been observed in AD (Arosio et al., 2004). Here, IL6 is linked to Alzheimer disease.