Tissue rejection after an organ transplant is least likely due to the action of
regulatory T cells
natural killer cells
B cells
cytotoxic T cells
macrophages
The Correct Answer is A
A. Regulatory T cells: Regulatory T cells suppress immune responses and promote tolerance to self and foreign antigens. They help prevent excessive immune reactions, including tissue rejection, making them least likely to cause rejection after an organ transplant.
B. Natural killer cells: NK cells can recognize and destroy cells lacking normal MHC expression, including transplanted tissue. They contribute to early immune responses that may lead to graft rejection.
C. B cells: B cells produce antibodies against foreign antigens on transplanted tissue, leading to humoral-mediated rejection. Their activity can directly damage the graft and trigger complement-mediated injury.
D. Cytotoxic T cells: Cytotoxic T cells recognize foreign MHC molecules on transplanted tissue and destroy those cells. They play a central role in cellular-mediated graft rejection and are a major contributor to transplant failure.
E. Macrophages: Macrophages are recruited to the graft site, where they participate in inflammation, antigen presentation, and tissue destruction. Their activity supports both cellular and humoral mechanisms of transplant rejection.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
A. Thymus:The thymus is largest and most active during childhood, producing T lymphocytes and establishing adaptive immunity. With age, it gradually atrophies and is replaced by fatty tissue, leading to reduced production of new T cells in older adults.
B. Appendix:The appendix contains lymphoid tissue, but it does not undergo significant atrophy with age. Its lymphoid function persists, albeit reduced, and it remains structurally present throughout life.
C. Spleen:The spleen retains its structure and immune functions throughout life. Although some immune efficiency may decline with age, it does not undergo true atrophy like the thymus.
D. Tonsils:Tonsils may undergo partial shrinkage after adolescence, but this is variable, and they do not exhibit the pronounced age-related atrophy characteristic of the thymus.
E. Lymph nodes:Lymph nodes may decrease slightly in size with aging, but they generally remain functional throughout life and do not atrophy to the same extent as the thymus.
Correct Answer is C
Explanation
A. Transporting dietary fats:The lymphatic system absorbs fats and fat-soluble vitamins from the digestive tract through specialized lymphatic vessels called lacteals. This is an important function that complements nutrient absorption and delivery to the bloodstream.
B. Draining excess interstitial fluid:Lymphatic vessels collect fluid that leaks from blood capillaries into tissues and return it to the circulatory system. This prevents edema and maintains fluid balance, making it a key function of the lymphatic system.
C. Transporting respiratory gases:Transport of oxygen and carbon dioxide is the primary role of the cardiovascular system, not the lymphatic system. Lymph does not carry respiratory gases, so this is not a function of lymphatic vessels.
D. Carrying out immune responses:The lymphatic system supports immune function by housing lymphocytes, filtering lymph through lymph nodes, and facilitating antigen detection. This makes immune defense a central role of the lymphatic system.
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