Aging and Immune Function

This chapter discusses the basis for age-dependent changes in immune function. Aging converts a fit, mature adult into an increasingly infirm one. The mechanisms of age-related immune decline suggest therapeutic strategies to protect aged patients from infectious and degenerative illnesses whose incidence and severity are influenced by immune function. The processes that lead to diminished protective immunity in the elderly may also contribute to senescent change in other tissues, and are clarified through study of the immune response. The generation of antigen-specific responses to foreign substances such as those introduced on infectious microbes, involves at least three distinct cell types. Antigen-presenting cells (APC) trap antigenic particles, digest them, and present antigenic peptides on their surface together with molecules of the major histocompatibility complex family. The immune system is the most suitable model, in which well-defined cell types produce well-defined molecules with predictable functions in vitro and in vivo. The role of immunosenescence in degenerative, infectious, and neoplastic illnesses may generate increasingly rational strategies for therapeutic intervention.