Question

Which of the following are involved in body defence?

• A. Neutrophils
• B. Lymphocytes
• C. Macrophages
• D. All the above

Answer 1

Answer: (D)

All the above

• The cells of the immune system can be categorized as lymphocytes (T-cells, B-cells and NK cells), neutrophils, and monocytes/macrophages. These are all types of white blood cells.
• Neutrophils are phagocytic cells that are also classified as granulocytes because they contain granules in their cytoplasm. These granules are very toxic to bacteria and fungi and cause them to stop proliferating or die on contact.
  
• B lymphocytes provide humoral immunity and T lymphocytes provide cellular immunity.
• Macrophages are efficient phagocytic cells that can leave the circulatory system by moving across the walls of capillary vessels. The ability to roam outside of the circulatory system is important because it allows macrophages to hunt pathogens with less limits. Macrophages can also release cytokines in order to signal and recruit other cells to an area with pathogens.
• Hence Neutrophils, Lymphocytes, and Macrophages are involved in body defense.
• So, the correct answer is 'All the above'.