The White Blood Cell (WBC) count is a measure of the number of white blood cells in a given volume of blood. WBCs are crucial components of the immune system, helping to fight infections, inflammation, and other diseases. Below are the key types of WBCs and their typical proportions in a differential WBC count:

Types of WBCs and Their Normal Ranges

1. Neutrophils
   • Function: Fight bacterial and fungal infections; the first responders to microbial infection.
   • Normal Range: 40%–70% of total WBC count.
2. Lymphocytes
   • Function: Include B cells, T cells, and natural killer (NK) cells; they are responsible for adaptive immunity and producing antibodies.
   • Normal Range: 20%–40% of total WBC count.
3. Monocytes
   • Function: Engulf and digest pathogens and debris; differentiate into macrophages or dendritic cells in tissues.
   • Normal Range: 2%–8% of total WBC count.
4. Eosinophils
   • Function: Fight parasitic infections and play a role in allergic reactions.
   • Normal Range: 1%–4% of total WBC count.
5. Basophils
   • Function: Release histamine during allergic reactions and help in immune response to parasites.
   • Normal Range: 0.5%–1% of total WBC count.

Total WBC Count

• Normal Range: 4,000–11,000 cells per microliter of blood (varies slightly by laboratory and population).

Clinical Significance

• Leukocytosis (High WBC count): May indicate infection, inflammation, stress, leukemia, or other conditions.
• Leukopenia (Low WBC count): May suggest bone marrow disorders, autoimmune diseases, severe infections, or effects of certain medications.