Which immune cells are the first responders to bacterial infection and are primarily responsible for phagocytosis?

Which immune cells are the first responders to bacterial infection and are primarily responsible for phagocytosis?

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

Answer: (C)

Neutrophils act as the body's rapid frontline responders to bacterial infection and are the primary cells responsible for phagocytosis. They are the most abundant white blood cells in the bloodstream and are equipped to reach infection sites quickly through chemotaxis. Once there, they engulf bacteria in a process called phagocytosis, and they kill the ingested microbes using an oxidative burst and antimicrobial enzymes stored in their granules. Their short lifespan means they act fast and are then cleared away as the infection is controlled, often with help from other immune cells. Monocytes arrive later and become macrophages in tissues, handling ongoing cleanup and antigen presentation. Lymphocytes are central to the adaptive immune response, coordinating targeted immunity. Eosinophils focus more on parasites and allergic responses, not the immediate bacterial phagocytosis role.

Neutrophils act as the body's rapid frontline responders to bacterial infection and are the primary cells responsible for phagocytosis. They are the most abundant white blood cells in the bloodstream and are equipped to reach infection sites quickly through chemotaxis. Once there, they engulf bacteria in a process called phagocytosis, and they kill the ingested microbes using an oxidative burst and antimicrobial enzymes stored in their granules. Their short lifespan means they act fast and are then cleared away as the infection is controlled, often with help from other immune cells.

Monocytes arrive later and become macrophages in tissues, handling ongoing cleanup and antigen presentation. Lymphocytes are central to the adaptive immune response, coordinating targeted immunity. Eosinophils focus more on parasites and allergic responses, not the immediate bacterial phagocytosis role.