In the order of decreasing numbers, which type of white blood cell comes first?

• A. Eosinophils
• B. Monocytes
• C. Lymphocytes
• D. Neutrophils

Answer: (D)

In the context of white blood cells, or leukocytes, the order of abundance in the bloodstream is important for understanding their roles in the immune system. Neutrophils are the most abundant type of white blood cells, constituting approximately 50-70% of the total white cell count. They are crucial for the body's defense against infection, particularly bacterial infections, as they are the first responders to sites of inflammation and infection.

Following neutrophils in quantity are lymphocytes, which play significant roles in the adaptive immune system, including T cells and B cells. Monocytes come next; they are larger cells that differentiate into macrophages and dendritic cells when they migrate into tissues, helping in phagocytosis and antigen presentation. Eosinophils are the least commonly found among these cells and are primarily involved in combating parasitic infections and mediating allergic reactions.

Understanding this hierarchy helps in clinical assessments and can guide healthcare professionals in diagnosing and managing various conditions, such as infections, allergies, and immune system disorders.