What is the most important type white blood cell?

The most important type of white blood cell is the neutrophil. Neutrophils are the most abundant type of white blood cell, making up 60-70% of all white blood cells. They are also the first type of white blood cell to respond to an infection. Neutrophils are phagocytic cells, which means that they can engulf and destroy foreign particles. They also release antimicrobial substances that can kill bacteria and other microorganisms. Neutrophils are essential for the body's defense against infection, and a deficiency in neutrophils can lead to serious infections.