DefinitionGranulocytes are a type of white blood cell that includes neutrophils, eosinophils, and basophils. They are called granulocytes because they are made of small granules, which contain important proteins.Granulocytes help the body fight bacterial infections. Persons who have lower numbers of granulocytes are more likely to get frequent and severe infections.Granulocytes are counted as part of a white blood cell differential test.