Leukocyte Types and Functions: A Guide to White Blood Cells

Major White Blood Cell Types

1. Neutrophils

Most abundant (50–70% of WBCs). First line of defense against bacterial and fungal infections. Short lifespan (12–24 hours). Phagocytic and release antimicrobial substances.

2. Lymphocytes

Involved in immune response. B cells produce antibodies; T cells mediate cell-mediated immunity. Long-lived (several years).

3. Monocytes

Phagocytic cells that differentiate into macrophages and dendritic cells. Role in inflammation and tissue repair.

4. Eosinophils

Defense against parasitic infections; release toxic substances that damage parasites. Also involved in allergic reactions.

5. Basophils

Least abundant (<1% of WBCs). Involved in allergic reactions and inflammation; release histamine and other inflammatory mediators.

6. Platelets

Not technically leukocytes but included for their role in immune response. Involved in blood clotting, wound healing, and release factors that activate inflammation and attract immune cells.