Blood aids in protecting the body from harmful bacteria and infections through the action of:

The role of white blood cells is pivotal in the body's immune response, providing protection against harmful bacteria and infections. These cells are a key component of the immune system and are specifically designed to identify, target, and destroy pathogens that can cause illness. White blood cells, also known as leukocytes, can differentiate into various types depending on the nature of the threat, including phagocytes that engulf and digest pathogens and lymphocytes that are essential for the adaptive immune response. This specialized function makes them critical in maintaining the body's defense mechanisms.

In contrast, red blood cells are primarily responsible for transporting oxygen throughout the body, while platelets play a crucial role in blood clotting. Plasma, the liquid component of blood, carries nutrients and waste products but does not have a direct role in fighting infections. Thus, the unique function of white blood cells in immune response underscores why they are integral to protecting the body against infection.