ABSTRACT
The term “eosinophile” was coined by Ehrlich in 1879 to describe granule-containing myelocytes that stained intensely with the acidic dye, eosin. Eosinophil development and maturation occurs largely in the bone marrow, and on release cells traffic rapidly to tissue, where their half life is close to 13 days. Eosinophil accumulation is likely to result from a balance between increased supply from bone marrow precursors, efflux of cells stored in a bone marrow pool, trafficking to sites of inflammation, adhesion to blood vessel endothelium, and egress into the tissue matrix, and finally increased survival owing to growth factor inhibition of apoptosis. A major effector limb of eosinophils is the release of the highly basic proteins major basic protein, eosinophil cationic protein, eosinophil peroxidase, and eosinophil-derived neurotoxin, or eosinophil protein X. Numerous stimuli have been implicated in eosinophil degranulation, including cytokines, adhesion molecules, and immunoglobulins, and different findings in different reports have confused this area of eosinophil biology.
