Eosinophilic granulocytes are a subpopulation of leucocytes and part of the innate immune cell pool. Additionally, they have homeostatic functions in different tissues. Classically, an increased number of eosinophils is associated with allergies and parasitic infections; however, eosinophilia can also be found in vasculitides and malignant tumors. The most important controlling factors of eosinophils are the cytokine interleukin 5 and eotaxins. Eosinophils are able to produce a broad range of signalling factors and toxic proteins, which are stored in cytoplasmic granules and can be quickly and specifically released when needed depending on the stimulus. To combat pathogens, eosinophils can catapult extracellular traps consisting of mitochondrial DNA and toxic proteins into the intercellular space. This review focuses on the basic structure, control and function of eosinophils in health and disease.
Keywords: Anti-eosinophil therapy; Cytoplasmatic granules; Eotaxin; Extracellular traps; Interleukin-5.