Aging, infections, and the immune system.

There is increasing clinical and laboratory evidence of decline in the immune system in the elderly patient with a simultaneous rise in the incidence of certain infections. Along with the involution of the thymus gland with age, there is evidence of decline in both T- and B-lymphocyte function and also in delayed hypersensitivity. In addition, there is evidence of an increase in various autoantibodies as a person ages. In recent years evidence has been presented of a genetic basis to this declining system. Because of these changes and because severe infections present more subtly in the elderly patient than in the young, the physician's suspicion for serious infections in the elderly should be heightened and immunization programs in the elderly adhered to.