[Phagocytes and phagocytosis 100 years after Metchnikoff. A current picture of the neutrophil leukocyte].
The observation of the amoebocytes of primitive organisms led ELIAS METSCHNIKOFF in 1882 to the idea that blood phagocytes--neutrophilic leukocytes in particular--could constitute an anti-microbial defense system. This was the beginning of the phagocyte theory which METSCHNIKOFF developed over many years and which in essence is still valid. The author sets out to provide an updated view of the neutrophil. Circulating neutrophils are end-cells. They develop in the bone marrow by a relatively long maturation process during which the characteristic azurophil and specific granules are formed. The granules are stored organelles. The azurophil granules contain microbicidal enzymes, i.e. myeloperoxidase and lysozyme, together with a large number of acid hydrolases and neutral proteases. The specific granules contain lysozyme, a collagenase, lactoferrin and transcobalamines. By subcellular fractionation a third kind of storage organelle has recently been found which is characterized by its gelatinase content. Circulating neutrophils are activated on microbial invasion--first in the blood, by chemotactic factors formed at the site of infection, and subsequently by the microbes themselves which are phagocytosed by the immigrating neutrophils. Chemotactic factors lead to directed migration and induce the secretion of enzymes which presumably facilitate this process. Phagocytosis results in the mobilization of neutrophil products in large quantities. The contact between the cell and the microorganism activates in the neutrophil membrane an oxidase which produces superoxide, and a phospholipase which releases arachidonic acid. The latter is then oxidized by cyclooxygenase and lipoxygenase. There is also massive liberation of enzymes from all three storage compartments. The production of superoxide is the essential process for the killing of a large variety of microorganisms.
D000486:Allergy and Immunology / Q000266:history; D001770:Blood Bactericidal Activity; D002633:Chemotaxis; D003594:Cytoplasmic Granules / Q000201:enzymology; D049672:History, 19th Century; D006801:Humans; D009113:Muramidase / Q000378:metabolism; D009504:Neutrophils / Q000201:enzymology / Q000276:immunology*; D010447:Peptide Hydrolases / Q000378:metabolism; D010544:Peroxidases / Q000378:metabolism; D010587:Phagocytosis; D012425:Russia (Pre-1917); D012802:Sicily; D013481:Superoxides / Q000096:biosynthesis
D013481:Superoxides; D010544:Peroxidases; D009113:Muramidase; D010447:Peptide Hydrolases
Phagozyten und Phagozytose hundert Jahre nach Metschnikoff. Ein aktuelles Bild des neutrophilen Leukozyten.