Title: Eosinophilic granulocyte
Description: Scheme electron microscopy.
A 11-15 mm cell with a bilobed nucleus (1) moderate amount of organelles, mitochondria (2), Golgi area (3), many vesicles (5) and numerous specific eosinophilic granules (4). These granules contain a central electron-dense angular crystalloid core embedded in a finely granular matrix.
The crystalloid consists of an alkaline protein (major basic protein or MBP), the matrix contains lysosomal hydrolases and lysophospholipase, myeloperoxidase, lactoferrin, eosinophilic cationic protein (ECP). Occasionally smaller light microscopic azurophilic granules might be present with a high content of acid phosphatase, arylsulfatase.
The phagocytic role of eosinophils is significantly less important than that of neutrophils. But they ingest immune complexes. Their major role is IgE-directed ADCC (antibody-dependent cell-mediated cytotoxicity) to eradicate parasites, i.e. the secretion of the content of the granules results in damage of the parasitic membrane. In allergic reactions, eosinophils contribute to tissue injury. The cells account for 2.7% of blood leucocytes. Their production is highly stimulated by IL-5, IL-3, GM-CSF. Upon activation and release of the granules also leukotrienes are produced which cause prolonged bronchoconstriction, mucus secretion, and increased vascular permeability.
Keywords/Mesh: blood, bone marrow, eosinophilic granulocyte, lysosome, specific granule, azurophilic granule, phagocytosis, histology, electron microscopy, POJA collection