Figure 1.

Cellular structure, receptors, and mediators of eosinophils. The pseudocolored composite electron micrograph of an eosinophil highlights cellular structures. Characteristic features of eosinophils include the multilobed nucleus, specific eosinophil granules, lipid bodies, and sombrero vesicles. Eosinophil granules contain cationic proteins, cytokines, growth factors, chemokines, and enzymes. The granule contents can be released upon stimulation. Lipid bodies are the place of synthesis for numerous lipid mediators. Granule contents can be released through sombrero vesicles. Eosinophils carry numerous cell surface receptors including chemokine receptors, Fc receptors, pattern recognition receptors, receptors for lipid mediators, cytokine receptors, complement receptors, and adhesion receptors. Abbreviations: 15-HETE, 15-hydroxyeicosatetraenoic acid; APRIL, a proliferation-inducing ligand; CCL, CC-chemokine ligand; CCR, CC-chemokine receptor; CXCL, CXC-chemokine ligand; CXCR, CXC-chemokine receptor; ECP, eosinophil cationic protein; EDN, eosinophil-derived neurotoxin; EGF, epidermal growth factor; EPX, eosinophil peroxidase; GMCSF, granulocyte-macrophage colony-stimulating factor; IFN, interferon; MBP, major basic protein; NGF, nerve growth factor; PDGF, platelet-derived growth factor; PAF, platelet-activating factor; SCF, stem cell factor; TGF, transforming growth factor; TNF, tumor necrosis factor; VEGF, vascular endothelial growth factor. The electron micrograph was generously provided by Dr. Isabelle Coppens, Johns Hopkins University, Baltimore, MD, USA.