High WBC refers to an abnormally elevated amount of white blood cells. White blood cells, or leukocytes, are a vital part of the body's ability to fight infection. White blood cells come in a variety of types, each with a unique set of immunological responsibilities. A decrease in white blood cells compromises immune function and leaves the individual vulnerable to infectious diseases. An increase in white blood cells causes a different set of health problems.
Infection
It is a normal occurrence that white blood cell counts will increase when the body is fighting off an infection. White blood cells called neutrophils and monocytes respond to the presence of bacterial cells by surrounding and digesting them, a process known as phagocytosis. White blood cells called lymphocytes also fight infection, but by a different mechanism, according to Gary Thibodeau, Ph.D., author of The Human Body in Health and Disease. When microbes are detected in the body, lymphocytes multiply, increasing the white blood cell count. These new lymphocytes become active in fighting infection by directly attacking the invasive organisms, or by inhibiting their ability to function.
Myeloproliferative Disorders
Blood cells are produced within the bone marrow. In some diseases, bone marrow cells will multiply uncontrollably, causing a subsequent increase in blood cell proliferation. The Arizona Telemedicine Program explains that disorders of this kind are known as myeloproliferative disorders. Myeloproliferative disorders arise from mutations of the genetic code within a bone marrow cell, which then begins to reproduce itself uncontrollably. Such unchecked cellular replication can result from DNA changes due to radiation exposure or genetically inherited factors. Myeloproliferative disorders can cause changes in the levels of both white and red blood cells. Examples of myeloproliferative diseases that can present an increase in white blood cells include essential thrombocythemia, and polycythemia vera.
Leukemia
Leukemia is a different type of bone marrow disorder that can result in high white blood cell counts. Leukemias can be chronic or acute, with acute leukemias often indicating an escalating condition that could potentially be fatal, according to the American Family Physician. Chronic leukemias may show few or no symptoms. In adults, chronic myelogenous leukemia is diagnosed by signs such as enlarged liver and lab tests that indicate an increase in the patient's white blood cell count, and a normal or decreased number of platelets.
References
- Arizona Telemedicine Program: Leukocytosis
- AmericanFamilyPhysicians: Leukocytosis: Basics of Clinical Assessment
- The Human Body in Health and Disease; Gary Thibodeau, PhD and Kevin Patton, PhD; 2002
