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White blood cells (also known as leukocytes and written WBC for short) the blood cells which are involved in immunity and defending the body against disease and illness.
White blood cells protect the body from antigen (foreign substances) or pathogens (disease causing organisms such as bacteria, viruses and fungi).
White blood cells are produced in the red bone marrow in the spaces of spongy bone tissue.
Most white blood cells do not last very long (only a few days) but are capable of a process called phagocytosis, which involves engulfing another organism/cell/substance to disarm it and prevent it from causing harm to the body.
There are five types of white blood cells:
- Basophils - 0.1-1.0% of total WBC; involved in allergic reactions and immune response; release histamine to enhance the body's reaction to an allergen
- Eosinophils - 2-4% of total WBC; they limit allergic response and help the immune system to destroy substances produced during the immune response; are slightly phagocytic
- Neutrophils - 60-70% of total WBC; are the first white blood cells that arrive at any infection or injured tissue; are effective phagocytes
- Monocytes - 3-8% of total WBC; move around the body and are called wandering macrophages or locate within a specific tissue in the body and are called fixed macrophages; are effective phagocytes
- Lymphocytes - 20-25% of total WBC; are the T cells (includes the helper T cells and cytotoxic T cells), B cells, natural killer (NK) cells; control the immune response and destroy any invading organisms
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Important white blood cells facts
- White blood cells are simplified as WBC
- White blood cells are also known as leukocytes
- A blood test with a full blood count (FBC) is required to show the levels of white blood cells in the blood
- White blood cells are used by the body as part of the immune system to remove pathogens (disease causing viruses and bacteria) from the body
- Lymphocytes, one of the white blood cell types, are responsible for controlling the immune system
- The white blood cells either contain granules in their cytoplasm and are called granulocytes - basophils, eosinophils, neutrophils; or do not not contain granules in their cytoplasm and are called agranulocytes - monocytes and lymphocytes
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Why white blood cells are important
The levels of white blood cells in the body:
| White Blood Cells | Value (per mcL ) |
| Neutrophils | 2.0 - 7.5 |
| Lymphocytes | 1.0 - 4.0 |
| Monocytes | 0.2 - 1.0 |
| Eosinophils | < 0.6 |
| Basophils | < 0.2 |
| Total WBC | 4.0 - 11.0 |
Low levels of white blood cells (called leukopaenia) can be caused by a number of reasons, including:
- Failure of the bone marrow to produce enough white blood cells
- Infection
- Tumours
- Radiation
- Certain diseases
High levels of white blood cells (called leukocytosis) can be caused by a variety of reasons, including:
references
- Marieb EM, Hoehn K. Human Anatomy & Physiology. 7th edition, 2006. Benjamin Cummings Publishing
- Tortora GJ, Derrickson BH. Principles of Anatomy & Physiology. 11th edition, 2005. Wiley Publishing
To learn more, go to the following web sites:
- Thinkquest Library - White Blood Cells (USA)
- National Library of Medicine - WBC (USA)
- Leukaemia Foundation (Australia)
- National Cancer Institute - Leukemia (USA)
