Editing Blood cell (section)

==White blood cells==
[[File:Red White Blood cells.jpg|thumb|Artificially colored electron micrograph of blood cells. From left to right: erythrocyte, thrombocyte, leukocyte.]]
[[White blood cell]]s or ''leukocytes'', are cells of the [[immune system]] involved in defending the body against both [[infectious disease]] and foreign materials. They are produced and derived from multipotent cells in the [[bone marrow]] known as [[hematopoietic stem cell]]s. Leukocytes are found throughout the body, including the blood and [[lymphatic system]]. There are a variety of types of white blood cells that serve specific roles in the human immune system. WBCs constitute approximately 1% of the blood volume.<ref>{{cite book |last1=Alberts |first1=Bruce |last2=Johnson |first2=Alexander |last3=Lewis |first3=Julian |last4=Raff |first4=Martin |last5=Roberts |first5=Keith |last6=Walter |first6=Peter |title=Molecular Biology of the Cell |date=2002 |publisher=Garland Science |location=New York |isbn=0-8153-4072-9 |edition=4th}}</ref>

White blood cells are divided into [[granulocyte]]s and [[agranulocyte]]s, distinguished by the presence or absence of [[Granule (cell biology)|granules]] in the cytoplasm. Granulocytes include [[basophils]], [[eosinophils]], [[neutrophils]], and [[mast cells]]. Agranulocytes include [[lymphocytes]] and [[monocytes]].

The condition of having too few white blood cells is [[leukopenia]], while having too many is [[leukocytosis]]. There are individual terms for the lack or overabundance of specific types of white blood cells. The number of white blood cells in circulation is commonly increased in the incidence of [[infection]].<ref>{{cite book |last1=Kumar |first1=Vinay |last2=Abbas |first2=Abul K. |last3=Fausto |first3=Nelson |last4=Aster |first4=Jon C. |title=Robbins and Cotran Pathologic Basis of Disease |date=2010 |publisher=Saunders/Elsevier |location=Philadelphia |isbn=978-1416031215 |edition=8th}}</ref> Many [[hematological cancer]]s are based on the inappropriate production of white blood cells.