What is the function of a draining lymph node?

Lymph nodes serve as critical components of the immune system, particularly in their role of filtering lymph fluid that circulates throughout the body. When an infection occurs in a particular region, fluid from the affected site—including pathogens, cellular debris, and antigens—flows into the surrounding lymphatic vessels and ultimately reaches a nearby draining lymph node.

The primary function of this draining lymph node is to filter the incoming lymph fluid. Inside the lymph node, immune cells such as lymphocytes are activated. These cells identify and respond to the pathogens or antigens present in the lymph, leading to the initiation of an immune response. This can involve the production of antibodies and the proliferation of various immune cells to combat the invading pathogens.

In contrast, the other choices describe functions that do not align with the primary and well-established role of draining lymph nodes. For example, lymph nodes do not filter blood directly; this function is primarily carried out by the spleen and various organs in the circulatory system. While lymph nodes can produce antibodies as part of the immune response, this is not their sole or defining function and occurs only as a reaction to the pathogens they encounter. Additionally, lymph nodes do not function to store excess nutrients; their primary purpose is related to immune