Polynuclear eosinophils Less represented than neutrophils. ✪ Morphology: At the level of the nucleus, the chromatin is identical to that of the neutrophil, it is to say in condensed form. In the cytoplasm we highlight specific granulations of orange-colored line after staining with MGG. It is an element which is a little more larger than the neutrophil because it measures between 12 and 17 micrometers. ✪ It can synthesize mediators which participate in inflammatory phenomena and in antibacterial and anti-parasitic phenomena, these are essentially cationic proteins. that we will find in the specific granules and we can also highlight phospholipid mediators which are newly formed, lysosomal enzymes such as collagenases, catalases, histaminases, phospholipases. A particular protein: lysophospholipase can polymerize and form crystalline formations: these are large Charcot Leyden crystals in the cytoplasm which are not surrounded by a membrane. ✪ These crystalloid formations can also be seen in the products of bronchoalveolar washing and therefore outside the cell. This lysophospholipase would protect the eosinophil of certain age toxic emissions. The polynuclear basophil is also capable of synthesizing this lysophospholipase and producing these crystals. ✪ The cationic proteins highlighted in the specific granules will appear at an early stage of development. ✪ In ME :We can object in this large orange granulation a crystalline inclusion and around this inclusion a sort of matrix which is clearer. The dye affinity of granules for acid dyes (eosin) is due to the richness in basic protein and that is what will give the cell this very characteristic orange appearance. The central crystalloid is made up of MBP (medium basic protein), in the matrix we will find other cationic proteins such as ECP (eosinophilic cationic protein), EDN and EDX which are neurotoxins. It is important to remember that these 3 proteins induce cytotoxicity (destruction of infectious agent cells) which is oxygen independent, they are not peroxidases ✪ We can highlight in the cationic proteins EPO which is a peroxidase specific to the eosinophil and this EPO will therefore have an oxygen-dependent cytotoxicity, it will allow the formation of oxygen radicals. However, eosi peroxide senophile does not have or little possibility of coupling oxygen radicals to halogen radicals, therefore a cytotoxicity capacity lower than that of the polynuclear neutrophil. They have a basal metabolism and production of oxygen radicals higher than that of polynuclear neutrophils. ✪ Eosinophils are capable of generating newly formed mediators: prostaglandins, certain leukotrienes which are chemotactic and vasoactive mediators which can induce a spasm at the vascular level by contraction of smooth muscle cells. These leukotrienes participate in maintaining the inflammatory phenomenon.
✪ Quantitative data: There is a marginal hen and a circulating pulse. The concentration is <0.5 giga/L. If this concentration increases, we will look for certain parasitoses; eosinophils accumulate in tissues where they can remain 2/4 days. They have a circulation time like the neutrophil of 24 hours. The eosinophil carries receptors, for example it can react by the eosinophil chemoattractant factor which is secreted by the polynuclear basophil. It can react to certain interleukins but also to certain leukotrienes, it has a lower phagocytosis capacity than that of neutrophils. In fact, the receptors for certain complement fractions have a lower affinity. There are also receptors for FC fragments of immunoglobulins which also have a lower affinity. The bactericidal action is less important than that of the neutrophil. ✪ A main function is the antiparasitic defense: it induces the secretion of T lymphocytes lion of the eosinophil stimulating promoter (ESP) which will specifically stimulate at the level of the hematopoietic bone marrow the eosinophil lineage therefore increase in their concentrations. On the other hand the parasite stimulates the production of plasmocytes which are cells derived from B lymphocytes and which are capable of generating antibodies. In purpose the parasite is covered with antibodies which will be recognized by the polynuclear eosinophil therefore destruction of the parasite either by phagocytosis or close contact and local extracellular release of enzymes destroying the parasite therefore inflammatory process more important than if internalization + destruction. ✪ The eosinophil intervenes by release of pro-inflammatory cytokine such as interleukin 1 or 6 and this cell must be considered immunocompetent due to these secretion products.*