Natural Killer Cell Activity in Patients With Dementia of the Alzheimer Type

To the Editor. —In Alzheimer's disease, several cellular alterations have been reported, not only about the central nervous system, but also about the non-neuronal tissues, including altered membrane fluidity of platelets1and decreased adhesiveness of fibroblasts.2Since the gene for amyloid precursor protein has been reported to be located on chromosome 21,3,4recent studies indicate that the abnormalities of Alzheimer's disease are not restricted to the brain. Patients with trisomy of chromosome 21 (Down's syndrome), who exhibit characteristics similar to Alzheimer's changes in the brain, have been reported as having abnormal natural killer cell activity.5This seems to be a plausible explanation for the increased frequency of infection and leukemia. To our knowledge, natural killer cell activity has never been described in Alzheimer's disease. Subjects and Methods. —Fifty-seven patients (9 men and 48 women; mean age; 78.5 years old) with dementia of the Alzheimer type (DAT)