The effect of aging on resistance to infection is of long-standing scientific interest. However, the current increase in the geriatric population and advances in pediatric medicine has stimulated intense research in this area. The problem is complex, particularly in the aged, where social, physiological, behavioral, and immunologic factors play key roles. It is the latter (immunologic factors) that will be the focus of this presentation.

The data from studies on aged humans and experimental animals with regard to the humoral and cellular immune systems are controversial and often lead to opposite conclusions. An attempt will be made to compare these data with what is known in marine mammals. Future direction of research in marine mammals will be emphasized.