What is the most numerous type of white blood cell called?

The most numerous type of white blood cell is the neutrophil. Neutrophils make up a significant portion of the white blood cell count, typically around 55-70% of the total leukocytes in a healthy adult. They play a crucial role in the immune response, particularly in defending the body against bacterial infections. Neutrophils are the first responders to sites of infection or inflammation, where they engulf and digest pathogens through a process called phagocytosis.

In contrast, lymphocytes, although essential for adaptive immunity, typically comprise about 20-40% of white blood cells, making them less abundant than neutrophils. Eosinophils and basophils are involved in combating parasitic infections and allergic reactions, respectively, but they are present in much lower numbers, often constituting only 1-4% and less than 1% of white blood cells, respectively. Thus, neutrophils are recognized as the predominant white blood cell type in terms of quantity and immediate immune function.