White blood cells produced by bone marrow play an important role in fighting infections and are the basis of the inflammatory response. They are also responsible for our immune system (antibody production). There are different types of leukocytes, including neutrophils, eosinophils, basophils, monocytes and lymphocytes. The white blood cell count represents the total of all of these fractions. The number of white blood cells is interpreted in light of the clinical examination and other blood count results.
A high number of white blood cells can be found in various conditions such as bacterial, viral, fungal and parasitic infections; inflammatory conditions such as rheumatoid arthritis, vasculitis, Crohn’s disease and ulcerative colitis; certain bone marrow disorders (leukemia, etc.); and in the allergic response (asthma, allergies), etc.
A reduced number of white blood cells can by caused by damaged or deficient bone marrow (toxins, chemotherapy, radiation, certain medications, myelodysplastic syndrome, vitamin B12 or folic acid deficiency, lymphoma or other cancer that has invaded the bone marrow). Autoimmune diseases (lupus, etc.), nutritional deficiencies, very severe infections (sepsis) and HIV (AIDS) infection will also lower the number of leukocytes.