Reduced natural killer cell activity in patients with dementia of the Alzheimer type.

We examined the natural killer (NK) cell activity in 50 patients with dementia of the Alzheimer type (DAT) and 37 age-matched normal controls. The NK cell activity in DAT was significantly lower than in the normal controls. The NK cell activity induced by either interferon-alpha (IFN-alpha) or interleukin-2 (IL-2) in DAT was also significantly lower than in the normal controls. There were no significant differences in the level of serum IL-2 and IFN-alpha between the two groups. As regards NK cell subsets, two-color flow cytometric analysis showed no significant differences between the percentages of Leu-11+ Leu-7- cells, Leu-11+ Leu-7+ cells and Leu-11- Leu-7+ cells in the two groups. Our results suggest that NK cells in DAT may have functional abnormalities and may provide important clues to fundamental cellular and molecular aberrations in DAT.