Changes in the Lymphoid System

Age-related changes in the lymphoid system (immune senescence) affect cellular and humoral immunity.

They include a significant decrease in humoral antibody response (especially the primary response), a decrease in T-cell function, production of antibodies that have less affinity for antigen, and increased production of autoidiotype antibody (which has an inhibitory effect on immune response). The resulting reduction in immunity may contribute to the increased susceptibility of the elderly to infections and malignancy.

In the healthy elderly, total lymphocyte and granulocyte counts have been reported as either normal or slightly decreased.