IFNG and Alzheimer disease: We first examined the frequencies of circulating Th1/Tc1 and Th2/Tc2 cells in patients with non-atopic AA, extrinsic or intrinsic AD-associated AA, and control normal subjects by measuring the percentages of CD4+IFN- γ+ cells (Th1), CD4+IL-4+ cells (Th2), CD4+IL-13+ cells (Th2), CD8+IFN-γ+ cells (Tc1), CD8+IL-4+ cells (Tc2), and CD8+IL-13+ cells (Tc2).