The lymphatic system plays a crucial role in the immune response by transporting lymph, a fluid containing immune cells and nutrients, throughout the body. It helps maintain fluid balance, absorb fats from the digestive system, and importantly, filters pathogens via lymph nodes. When foreign invaders are detected, lymph nodes activate lymphocytes, initiating a targeted immune response. Thus, the lymphatic system is vital for both defense mechanisms against infections and overall homeostasis in the body.