Title: Eosinophilic granulocyte in peripheral blood smear (human)
Description: Stain: May-Grünwald-Giemsa (MGG).
The eosinophil (11-15 mm) contains a bilobed nucleus and numerous large solitary brown-orange granules. The eosinophils are the first line of defense against parasites but also take part in allergic reactions (bronchial asthma). Arrow (↓) points to two platelets.
Background: This cell is considered phagocytic with a special affinity for antigen-antibody complexes. Eosinophils are normally present in peripheral tissues, especially in mucosal linings of the respiratory, gastrointestinal, and genitourinary tracts, and their numbers can increase by recruitment in the setting of inflammation. IL-5, released by Th2 cells enhances the ability of eosinophils to release granule contents on cross-linking of FcE-receptors. The granule proteins are toxic to parasites and may also injure normal tissue. The granules contain microbicidal substances such as peroxidase, major basic protein (MBP) and eosinophilic cationic protein (ECP). These substances disrupt the membrane of parasites; basophils are caused to release histamine; and heparin is neutralized. Activated eosinophils, like mast cells and basophils, produce and release lipid mediators including PAF, prostaglandins and leukotrienes (LTC4, LTD4, LTE4). Also a variety of cytokines are produced by them (IL-3, IL-5, IL-8, IL-10, GM-CSF etc).
Keywords/Mesh: blood, bone marrow, eosinophilic granulocyte, histology, POJA collection