What Is WBC (White Blood Cell Count) in a Blood Test?

WBC stands for White Blood Cell Count. White blood cells are your immune system's defense against infection and inflammation.

Normal Range

• 4,500–11,000 cells/µL for adults

The Five Types

• Neutrophils (40–60%) — bacterial defense
• Lymphocytes (20–40%) — viral defense, antibodies
• Monocytes (2–8%) — become macrophages
• Eosinophils (1–4%) — parasites, allergies
• Basophils (0.5–1%) — histamine release

High WBC Causes

• Bacterial infection — most common cause
• Inflammation — autoimmune disease
• Physical stress — exercise, surgery
• Leukemia — markedly elevated
• Corticosteroid use
• Smoking

Low WBC Causes

• Viral infection
• Bone marrow suppression — chemotherapy
• Autoimmune disease — lupus
• Certain medications
• HIV/AIDS
• Severe malnutrition