Leukocytes (White Blood Cells): Types and Functions

Leukocytes are immune cells produced in bone marrow. They increase during infection, inflammation, or injury. Two main categories:

Granulocytes (have cytoplasmic granules)

• Neutrophils (50–70%): Phagocytic, first responders, inflammatory role.
• Eosinophils (1–3%): Anti-parasitic, allergic responses, asthma inflammation.
• Basophils (<1%): Release histamine, mediate inflammation.

Agranulocytes (no granules)

• Lymphocytes (20–30%): B cells (antibodies), T cells (kill infected cells, regulate immunity).
• Monocytes (5–10%): Phagocytic; differentiate into tissue macrophages.