A patient presents with swollen, tender lymph nodes near an infected wound. How should the nurse interpret the role of these lymph nodes in the immune response?

A. They primarily produce lymph fluid to transport nutrients and waste products away from the infection site is incorrect because lymph fluid is produced by the interstitial fluid entering lymphatic vessels, not by lymph nodes themselves. Lymph nodes filter this fluid rather than generate it. B. They store excess fluid from the bloodstream to prevent swelling in the infected tissue is incorrect because lymph nodes do not act as reservoirs for fluid. Swelling is managed through lymphatic drainage, but the nodes’ main role is immune surveillance, not fluid storage. C. They regulate blood pressure around the infected area by constricting blood vessels is incorrect because lymph nodes do not influence blood vessel constriction or local blood pressure. Vascular tone is regulated by the cardiovascular and autonomic systems. D. They are filtering lymph fluid, trapping pathogens, and activating immune cells to fight the infection is correct because lymph nodes contain lymphocytes (B cells and T cells) and macrophages that detect and respond to pathogens carried in the lymph. When an infection is present, the nodes become enlarged and tender as immune cells proliferate and actively fight the infection. This swelling is a sign of the immune response in action.