Lymphocyte concanavalin A capping: a similarity between Down's syndrome and early onset primary degenerative dementia.

Lymphocyte capping with concanavalin A was studied in adult patients with Down's syndrome and aged patients with primary degenerative dementia. In both disorders a decreased capping was found as compared with age-matched and clinically relevant control groups. Colchicine had a strong enhancing effect on capping in Down's syndrome. In primary degenerative dementia the enhancing effect of colchicine was restricted to a subgroup of patients with onset of the dementing illness before the age of 80 years.