Which of the following changes occurs in the immune system with aging?

With aging, the immune system undergoes several changes, leading to alterations in its function. One significant change is the increase in autoantibody synthesis. As individuals age, there is a tendency for the immune system to become less tolerant of self-antigens, resulting in the production of autoantibodies. These autoantibodies are antibodies that mistakenly target and react with a person's own tissues, leading to autoimmune phenomena.

This increase in autoantibody synthesis correlates with the age-related decline in the function of regulatory T-cells and other mechanisms that normally maintain tolerance to self-antigens. Consequently, older individuals have a higher prevalence of autoimmune diseases due to this heightened production of autoantibodies.

While there are variations in immune cell populations with aging, such as changes in CD4 and CD8 T-cell counts, the most distinctive and relevant change in the context of the immune system and aging is the increased synthesis of autoantibodies.