A 55-year-old patient tells the nurse that he seems to be getting "more colds" as he gets older. Which of the following would explain what the patient is experiencing?

Question

1. The thyroid gland begins to malfunction after the 4th decade of life.
2. The thymus gland shrinks, reducing the maturation and differentiation of T cells needed to fight infections.
3. The immune system has difficulty determining self from non-self cells.
4. The body has difficulty recognizing mutated cells.

Answer 1

2

Rationale: The function of the immune system declines with age. The thymus gland, where T lymphocytes mature and differentiate, begins to atrophy early in life and continues to shrink until a person reaches middle age. Although T lymphocytes continue to be produced, their maturation and differentiation into the various functional T cells decreases. This places the older patient at higher risk for increased frequency and severity of infections accompanied by a decreased ability to resolve the infection. The thyroid gland plays no significant role in immunity. The ability of the immune system to discriminate between antigens that are "self" from those that are "non-self" would explain the increased incidence of autoimmune diseases in middle age and older patients. The body's immune system becoming less efficient at recognizing and destroying mutated cells can explain the increased incidence of cancer in the older adult.