Delayed hypersensitivity in Alzheimer's disease following BCG immunostimulation.

Forty-four patients with Alzheimer's disease were evaluated for delayed hypersensitivity responses using five ubiquitous antigens. Compared with a nondemented age-matched population, these patients evidenced a large number of deficient responses, especially in the zero-response group. Twenty-three patients were randomly selected for immunostimulation using BCG vaccine. The skin tests were repeated 2 weeks after a series of four weekly intradermal injections of BCG. Only 2 of 13 nonresponsive patients failed to convert at least one negative result into a positive response, and seven became normal.