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Leukocyte: Difference between revisions
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'''Leukocytes''', also called '''white blod cells''' (WBCs), are a population of cells in the blood responsible for immune response, inflammation, and microbe defence. These are always present in the blood, with their numbers increasing in response to infection or inflammation. They are a major part of the immune system. | <section begin="physiology" /><section begin="clinical biochemistry" />'''Leukocytes''', also called '''white blod cells''' (WBCs), are a population of cells in the blood responsible for immune response, inflammation, and microbe defence. These are always present in the blood, with their numbers increasing in response to infection or inflammation. They are a major part of the immune system.<section end="clinical biochemistry" /> | ||
If the number of WBCs is elevated above 11 000/µL there is ''leukocytosis''. The body produces more WBCs in response to most infections and inflammations in the body. An elevated white blood count on a blood test is almost always indicative of an ongoing infection or inflammation in the patient. In theory strenuous exercise and emotional stress can cause leucocytosis too. | If the number of WBCs is elevated above 11 000/µL there is ''leukocytosis''. The body produces more WBCs in response to most infections and inflammations in the body. An elevated white blood count on a blood test is almost always indicative of an ongoing infection or inflammation in the patient. In theory strenuous exercise and emotional stress can cause leucocytosis too. | ||
If the number of WBCs is below 4 000/µL there is ''leukopaenia''. This occurs if there is damage to the bone marrow, due to toxic effects from drugs, [[radiation]], [[chemotherapy]], or cancer of the bone marrow, such as [[myelodysplastic syndrome]] or [[leukaemia]]. | If the number of WBCs is below 4 000/µL there is ''leukopaenia''. This occurs if there is damage to the bone marrow, due to toxic effects from drugs, [[radiation]], [[chemotherapy]], or cancer of the bone marrow, such as [[myelodysplastic syndrome]] or [[leukaemia]]. | ||
<section begin="clinical biochemistry" /> | |||
== Types == | == Types == | ||
There are multiple subgroups of leukocytes, including granulocytes, lymphocytes, and monocytes. Neutrophils, eosinophils and basophils all contain granules and have a granular appearance. For this reason, they’re together called ''granulocytes''. Monocytes and lymphocytes don’t have granular appearance and are sometimes called ''agranulocytes''. | There are multiple subgroups of leukocytes, including granulocytes, lymphocytes, and monocytes. Neutrophils, eosinophils and basophils all contain granules and have a granular appearance. For this reason, they’re together called ''granulocytes''. Monocytes and lymphocytes don’t have granular appearance and are sometimes called ''agranulocytes''. | ||
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A good way to remember the order of white blood cells in decreasing order from most abundant to least abundant is the pneumonic ''never let monkeys eat bananas.'' N – L – M – E – B. | A good way to remember the order of white blood cells in decreasing order from most abundant to least abundant is the pneumonic ''never let monkeys eat bananas.'' N – L – M – E – B. | ||
<section end="clinical biochemistry" /> | |||
=== Neutrophils === | === Neutrophils === | ||
Neutrophil granulocytes, often called just neutrophils, are the most abundant leukocyte in the blood, accounting for approx 60% of them. They have a segmented nucleus. | Neutrophil granulocytes, often called just neutrophils, are the most abundant leukocyte in the blood, accounting for approx 60% of them. They have a segmented nucleus. | ||
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Like eosinophils, basophils are important in parasitic infections. Basophilia often occurs with eosinophilia. | Like eosinophils, basophils are important in parasitic infections. Basophilia often occurs with eosinophilia. | ||
The granules of basophils contain [[histamine]] and [[heparin]] (an anticoagulant). | The granules of basophils contain [[histamine]] and [[heparin]] (an anticoagulant).<section end="physiology" /> | ||
<section begin="clinical biochemistry" /> | |||
== Leukocytes as a lab test == | == Leukocytes as a lab test == | ||
Measurement of the number of leukocytes in the blood, a leukocyte count, is often used in the laboratory evaluation of infection or inflammation, leukaemia, and bone marrow. One can order the lab to just measure the number of leukocytes, or one can order the lab to measure the number of each type of leukocytes, called a complete blood count (CBC). Doing a CBC gives more information than a plain leukocyte count, but the information may not always be useful. | Measurement of the number of leukocytes in the blood, a leukocyte count, is often used in the laboratory evaluation of infection or inflammation, leukaemia, and bone marrow. One can order the lab to just measure the number of leukocytes, or one can order the lab to measure the number of each type of leukocytes, called a complete blood count (CBC). Doing a CBC gives more information than a plain leukocyte count, but the information may not always be useful. | ||
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|Basophilia | |Basophilia | ||
|Allergic reaction, [[chronic myeloid leukaemia]] | |Allergic reaction, [[chronic myeloid leukaemia]] | ||
|} | |}<section end="clinical biochemistry" /> | ||
[[Category:Immunology]] | [[Category:Immunology]] | ||
[[Category:Laboratory Medicine]] | [[Category:Laboratory Medicine]] | ||
[[Category:Physiology]] | [[Category:Physiology]] | ||