What is the primary function of white blood cells in the human body?

White blood cells, also known as leukocytes, play a critical role in the immune system, making their primary function the protection of the body against infections. They are essential components of the body's defense mechanism, actively identifying and neutralizing pathogens such as bacteria, viruses, and other foreign invaders. Different types of white blood cells, including lymphocytes, neutrophils, and macrophages, perform specialized functions that contribute to the immune response. For instance, lymphocytes are key in recognizing specific antigens, while neutrophils are often the first responders to sites of infection.

The design of the immune system emphasizes the role of white blood cells in maintaining health, enabling the body to respond swiftly to pathogens and remember them for future encounters, thus providing immunity. This critical function underscores the importance of white blood cells in safeguarding the body from illness and infection.