Immunological studies in senile dementia of the Alzheimer type: evidence for enhanced suppressor cell activity.

To examine immunological variables in senile dementia of the Alzheimer type (SDAT), we compared SDAT patients with elderly and young controls with regard to concanavalin A (Con A)-induced suppression, lymphocyte proliferation, interferon production, and serum immunoglobulin levels. The results showed exaggerated Con A suppression and reduced lymphocyte proliferation in SDAT patients compared to elderly control subjects. Interferon production after stimulation by Con A and immunoglobulin levels did not differ between SDAT and elderly control subjects. The results suggest impaired immunoregulatory mechanisms in patients with SDAT that may be related to the cause or course of SDAT. Alternatively, these immunological changes may be secondary to pathological changes in the central nervous system.