eosinophil

eosinophil, type of white blood cell (leukocyte) that is characterized histologically by its ability to be stained by acidic dyes (e.g., eosin) and functionally by its role in mediating certain types of allergic reactions. Eosinophils, along with basophils and neutrophils, constitute a group of white blood cells known as granulocytes. Eosinophils contain large granules, and the nucleus exists as two nonsegmented lobes. In addition, the granules of eosinophils typically stain red, which makes them easily...