Circulating interleukin-15 in dementia disorders.

The objective of this study was to assess the role of interleukin-15 (IL-15) as a potential marker of immune reactions in patients with Alzheimer's disease and vascular dementia. The authors measured by immunoassay serum IL-15 levels in 20 patients with Alzheimer's disease and 15 patients with vascular dementia and compared them with serum IL-15 levels in 15 healthy subjects. The authors also studied the effect of treatment with acetylcholinesterase inhibitors (AChEI) on serum IL-15 levels. Patients with Alzheimer's disease were found to have significantly lower serum IL-15 levels compared with healthy subjects and patients with vascular dementia. Healthy subjects and patients with vascular dementia did not differ between each other. Age, sex, disease duration, and Mini-Mental State Examination score did not affect IL-15 levels in any of the groups. Treatment with AChEI had no influence on IL-15 concentrations. The findings suggest that IL-15 is not implicated in the pathogenetic mechanisms of Alzheimer's disease and vascular dementia. An immune hyporesponsiveness at some point during disease development may be responsible for the lower levels of IL-15 and other cytokines in Alzheimer's disease patients.