Clozapine has a risk of agranulocytosis. Which white blood cell type is most affected?

• A. Neutrophils
• B. Erythrocytes
• C. Platelets
• D. Lymphocytes

Answer: (A)

Clozapine’s dangerous hematologic risk is agranulocytosis, a severe drop in a specific white blood cell type essential for fighting infections: neutrophils. Neutrophils make up the vast majority of circulating white cells and respond quickly to bacterial invaders. When the drug suppresses bone marrow activity, neutrophil production falls most dramatically, leading to a critically low absolute neutrophil count that leaves the patient highly susceptible to infections. Erythrocytes (red blood cells) and platelets can be affected by other conditions, but they are not the primary cells reduced in clozapine-induced agranulocytosis. Lymphocytes are part of the adaptive immune system, but the hallmark cytopenia with clozapine is neutropenia leading to agranulocytosis. Regular monitoring of the neutrophil count is essential during treatment to catch this dangerous drop early.