T-lymphocyte function in Alzheimer's disease.

T-lymphocyte function in Alzheimer's disease (AS) was evaluated by means of delayed type hypersensitivity (DTH) and mitogen responsiveness using concanavalin A (Con A) and BCG vaccine as stimulators. DTH and the response to Con A was significantly lower in AD than in normal aging. The Con A response included one group in which the thymidine uptake was lower than the minimum normal response while another group was within the normal range. This subset could account for the inconsistency in previous reports of T-cell function in AD.