American Board of Surgery Qualifying Exam (ABS QE) Practice Test

How does aging affect the response of T cells?

1. They become more efficient

2. They are produced in greater numbers

3. They exhibit a decreased ability to respond to new antigens

4. They show increased activation in response to infections

The correct answer is: They exhibit a decreased ability to respond to new antigens

As individuals age, the immune system undergoes various changes, particularly affecting T cells, which are a critical component of the adaptive immune response. One significant aspect of aging is that T cells exhibit a decreased ability to respond to new antigens. This is largely due to several factors, including a reduction in the diversity of the T cell receptor repertoire. Older individuals have a less robust immune history, resulting in a diminished capacity to recognize and respond to novel pathogens that the body has not encountered before. Additionally, the thymus, where T cells mature, gradually involutes with age, leading to a decrease in the production of naive T cells. This results in a lower pool of T cells that are ready to respond to new infections. Overall, the diminished responsiveness to new antigens contributes to increased susceptibility to infections and a reduced efficacy of vaccines in the elderly population. In contrast, options suggesting that T cells become more efficient or are produced in greater numbers do not accurately reflect the immune dynamics seen in aging. Similarly, the idea that T cells show increased activation in response to infections does not align with the reduced responsiveness observed, as older adults often struggle to mount a vigorous immune response when faced with new challenges.