Microbiology Practice Exam

What function do neutrophils primarily serve in the immune system?

1. Formation of antibodies

2. Phagocytosis

3. Histamine production

4. Cytotoxic activity

The correct answer is: Phagocytosis

Neutrophils serve a crucial role in the immune system primarily through the process of phagocytosis, which is the engulfing and digestion of pathogens such as bacteria and fungi. These white blood cells are among the first responders to sites of infection and inflammation. Once they are attracted to the area, they utilize various mechanisms to recognize, attach to, and internalize these pathogens. Once inside the neutrophil, pathogens are contained in a vesicle called a phagosome, which then merges with granules filled with enzymes and antimicrobial substances. This allows neutrophils to effectively break down and eliminate invading microorganisms, making them essential for the body's innate immune response. While the other functions listed in the options are important to the immune system, they are either attributed to different cells or serve different roles. Antibody formation is primarily carried out by B lymphocytes, histamine production is mainly the function of mast cells and basophils in response to allergens, and cytotoxic activity is typically associated with certain T cells. Thus, the primary function of neutrophils distinctly focuses on phagocytosis as their main defensive mechanism.