What components of the blood are responsible for producing substances that help the body fight infection?

White blood cells are crucial in the body's immune response and play a fundamental role in fighting infection. These cells are part of the immune system and are responsible for identifying and attacking pathogens, such as bacteria and viruses. They produce various substances, including antibodies and cytokines, which help orchestrate the immune response and enhance the body's ability to defend itself against infections.

Different types of white blood cells, such as lymphocytes and phagocytes, each have specific functions that contribute to immunity. Lymphocytes, for example, are vital in recognizing specific antigens and can produce antibodies, while phagocytes can engulf and destroy pathogens directly.

In contrast, red blood cells primarily transport oxygen throughout the body and are not involved in the immune response. Platelets are essential for blood clotting, aiding in wound healing, and plasma serves as the liquid medium for transporting blood cells and nutrients but does not produce substances for fighting infections directly. This specialization of white blood cells for immune functions underscores their critical role in the body's ability to combat infections effectively.