Which cells are the first responders in acute inflammation and are primarily responsible for phagocytosis of bacteria?

Which cells are the first responders in acute inflammation and are primarily responsible for phagocytosis of bacteria?

• A. Neutrophils
• B. Lymphocytes
• C. Macrophages
• D. Dendritic cells

Answer: (A)

In acute inflammation, neutrophils are the first responders and the main cells that phagocytose bacteria. They rush to the site of infection within hours, attracted by chemotactic signals like IL-8, C5a, and bacterial products. Neutrophils are equipped with granules containing enzymes and reactive oxygen species that kill engulfed microbes, making them the primary defense in early bacterial infections. Macrophages, coming from monocytes, arrive a bit later and continue phagocytosis while coordinating resolution and tissue repair. Lymphocytes are involved in adaptive immunity, and dendritic cells act mainly as antigen-presenting cells, though they can perform some phagocytosis. The combination of rapid arrival and efficient microbial killing makes neutrophils the best answer.

In acute inflammation, neutrophils are the first responders and the main cells that phagocytose bacteria. They rush to the site of infection within hours, attracted by chemotactic signals like IL-8, C5a, and bacterial products. Neutrophils are equipped with granules containing enzymes and reactive oxygen species that kill engulfed microbes, making them the primary defense in early bacterial infections. Macrophages, coming from monocytes, arrive a bit later and continue phagocytosis while coordinating resolution and tissue repair. Lymphocytes are involved in adaptive immunity, and dendritic cells act mainly as antigen-presenting cells, though they can perform some phagocytosis. The combination of rapid arrival and efficient microbial killing makes neutrophils the best answer.