What function do white blood cells in lymph nodes serve?

White blood cells in lymph nodes play a crucial role in the immune system, specifically in defending the body against pathogens such as bacteria, viruses, and other foreign invaders. Lymph nodes serve as a filtering station, where lymph fluid—containing infections and other harmful substances—is collected for analysis.

When pathogens are detected, the white blood cells, including lymphocytes, respond by proliferating and releasing antibodies that target and neutralize these threats. They also help in the process of phagocytosis, where they engulf and destroy pathogens. This protective function is vital for maintaining health and preventing infections from spreading throughout the body.

The other options refer to functions unrelated to the immune response. While energy production and blood pressure regulation are important physiological processes, they are not the primary responsibilities of white blood cells in lymph nodes. Digestive assistance is also outside the scope of what lymph nodes and white blood cells are designed to accomplish.