Which type of white blood cell is the most common and helps defend the body against infections?

Neutrophils are the most common type of white blood cell and play a vital role in the immune system's response to infections. They are a key component of the body's defense mechanism, particularly in combating bacterial infections. Neutrophils are the first responders to sites of infection, where they engage pathogens through processes such as phagocytosis, in which they engulf and digest bacteria and debris. Their abundance in the bloodstream provides a rapid response capability, allowing the immune system to quickly mobilize to areas where pathogens are present.

The other types of white blood cells, while important, serve different functions in the immune response. Lymphocytes, for example, are primarily involved in the adaptive immune response and include T cells and B cells, which are crucial for targeting specific pathogens and developing long-term immunity. Monocytes can differentiate into macrophages that help in the cleanup of dead cells and debris, but they are not the primary line of defense against acute infections. Eosinophils are mainly involved in combating parasitic infections and play a role in allergic reactions but are not the most prevalent white blood cells in ordinary infections.