The decrease of CD8-positive lymphocytes in Alzheimer's disease.

The aim of this study was to analyze the possible association of the changes in systemic immunity in the neurodegenerative diseases and in brain atrophy per se. Therefore we enumerated the numbers and proportions of the CD3-, CD4- and CD8-positive cells and B-lymphocytes in peripheral blood of 136 patients with various neurodegenerative disorders of the brain and 58 healthy age-matched controls. The selective decrease of the CD8-positive lymphocytes was demonstrated in the patients with Alzheimer's disease. In contrast, in the patients with brain atrophy of unknown origin and in the patients with vascular dementia the number of the CD8-positive cells tended to increase. The results suggest that brain degenerative changes are associated with changes in the systemic immunity and the changes are linked with the underlying disorder more than brain degeneration per se.