Background: Until recently, new data on immune aspects of Alzheimer's disease (AD) have suggested that some facets of AD pathogenesis may be immune related. However, the effects of dementia itself on immune function have not been considered.
Aim: To compare the distribution of peripheral blood lymphocyte subsets and their function in patients with AD and other dementias.
Methods: Peripheral blood lymphocyte numbers, T cell subset distribution, proliferative responses to mitogens and suppressor cell assay were studied in a well characterised group of patients with AD, and compared to patients with other forms of dementia. Age and sex matched elderly controls were screened to exclude dementia, and young controls were medical, paramedical and laboratory staff. Analysis of variance (ANOVA) and student's test were used for statistical analysis.
Results: The CD8+ lymphocyte population was reduced in AD and in other forms of dementia, when compared with non-demented elderly and young controls. Concanavalin A induced lymphocyte transformation was reduced in all dementia groups and in elderly compared with young controls. The changes in T cell numbers and function were not specific for Alzheimer's disease, but were found also in other forms of dementia.