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Granulocytes are a type of white blood cell that has small granules, which contain proteins. The specific types of granulocytes are neutrophils, eosinophils, and basophils.

Granulocytes, specifically neutrophils, help the body fight bacterial infections. The number of granulocytes in the body usually increases when there is a serious infection. People with a lower number of granulocytes are more likely to develop bad infections more often.

Granulocytes are counted as part of a white blood cell differential test.


Hall JE. Resistance of the body to infection. In: Hall JE. Guyton and Hall Textbook of Medical Physiology. 12th ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 33.

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  • Last reviewed on 1/27/2015
  • Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital, Boston, MA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.

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