Which leukocyte is typically the first to arrive at a site of acute infection and is highly phagocytic?

Which leukocyte is typically the first to arrive at a site of acute infection and is highly phagocytic?

• A. Lymphocyte
• B. Monocyte
• C. Neutrophil
• D. Eosinophil

Answer: (C)

Neutrophils are the body's rapid first responders to acute infection. They exit the bloodstream quickly in response to chemotactic signals released at the site of infection, such as bacterial products and inflammatory mediators, and they migrate into tissues to confront the invading microbes. These cells are highly phagocytic and equipped with potent lysosomal enzymes in their granules, allowing them to engulf and digest bacteria efficiently. They also generate reactive oxygen species in a respiratory burst to kill ingested pathogens. Because they are the most abundant leukocytes and have a short lifespan, they are perfectly suited for an immediate, frontline attack and cleanup in acute bacterial infections. Lymphocytes handle targeted, adaptive immune responses and tend to arrive after the initial neutrophil wave. Monocytes circulate and later differentiate into macrophages in tissues, contributing to phagocytosis and cleanup, but they come in after neutrophils. Eosinophils specialize in responses to parasites and allergic reactions and are not the primary phagocytes in acute bacterial infections.

Neutrophils are the body's rapid first responders to acute infection. They exit the bloodstream quickly in response to chemotactic signals released at the site of infection, such as bacterial products and inflammatory mediators, and they migrate into tissues to confront the invading microbes. These cells are highly phagocytic and equipped with potent lysosomal enzymes in their granules, allowing them to engulf and digest bacteria efficiently. They also generate reactive oxygen species in a respiratory burst to kill ingested pathogens. Because they are the most abundant leukocytes and have a short lifespan, they are perfectly suited for an immediate, frontline attack and cleanup in acute bacterial infections.

Lymphocytes handle targeted, adaptive immune responses and tend to arrive after the initial neutrophil wave. Monocytes circulate and later differentiate into macrophages in tissues, contributing to phagocytosis and cleanup, but they come in after neutrophils. Eosinophils specialize in responses to parasites and allergic reactions and are not the primary phagocytes in acute bacterial infections.