Which type of blood cell is primarily responsible for defending the body against infections?

White blood cells, also known as leukocytes, play a crucial role in the immune system by defending the body against infections. They are part of the body's response to pathogens such as bacteria, viruses, and other foreign invaders. White blood cells can be further classified into several types, including neutrophils, lymphocytes, monocytes, eosinophils, and basophils, each with specific functions in identifying and eliminating harmful microorganisms.

In contrast, red blood cells are primarily responsible for transporting oxygen to tissues and removing carbon dioxide from the body, but they do not participate in immune defense. Platelets are essential for blood clotting and help prevent bleeding, while plasma cells are a type of white blood cell specifically involved in producing antibodies but do not represent the entire function of the immune response. This emphasis on the role of white blood cells in immunity reinforces their importance in maintaining health and combating infections.