Defend against helminthic infections (major basic protein).- Bilobate nucleus.- Packed with large eosinophilic granules of uniform size.- Highly phagocytic for antigen-antibody complexes.

- Produce histaminase, major basic protein (MBP, a helminthotoxin), eosinophil peroxidase, eosinophil cationic protein, and eosinophil-derived neurotoxin.

Causes of eosinophilia: parasites, neoplasia (eg, Hodgkin lymphoma), asthma, allergic processes, Churg-Strauss syndrome, chronic adrenal insufficiency, myeloprolierative disorders