Which white blood cell characteristically has a multi-lobed nucleus and is a key defender against bacterial infections?

Which white blood cell characteristically has a multi-lobed nucleus and is a key defender against bacterial infections?

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

Answer: (A)

White blood cells that are the frontline defense against bacterial infections are neutrophils. They have a multi-lobed, segmented nucleus, typically with 2–5 distinct lobes, which gives that characteristic multi-lobed look under the microscope. Neutrophils are the most abundant WBCs and arrive at infection sites quickly. They perform phagocytosis, engulfing bacteria into a phagosome, and release enzymes and antimicrobial substances from their granules to kill the invaders. They also generate reactive oxygen species through a respiratory burst to destroy engulfed bacteria. This rapid response and strong bactericidal capacity make neutrophils the key defenders against bacterial infections. Other white blood cells—lymphocytes (adaptive immunity), eosinophils (parasites and allergy modulation), and basophils (inflammatory signaling and histamine release)—have different primary roles, so they are not the main bacteria-fighting cells in the way neutrophils are.

White blood cells that are the frontline defense against bacterial infections are neutrophils. They have a multi-lobed, segmented nucleus, typically with 2–5 distinct lobes, which gives that characteristic multi-lobed look under the microscope. Neutrophils are the most abundant WBCs and arrive at infection sites quickly. They perform phagocytosis, engulfing bacteria into a phagosome, and release enzymes and antimicrobial substances from their granules to kill the invaders. They also generate reactive oxygen species through a respiratory burst to destroy engulfed bacteria. This rapid response and strong bactericidal capacity make neutrophils the key defenders against bacterial infections. Other white blood cells—lymphocytes (adaptive immunity), eosinophils (parasites and allergy modulation), and basophils (inflammatory signaling and histamine release)—have different primary roles, so they are not the main bacteria-fighting cells in the way neutrophils are.