Disorders of polymorphonuclear leukocytes relevant to infection

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The idea that phagocytic cells protect the host against attack by microorganisms is a very old one, first expounded clearly by Metchnikoff. Much of our detailed knowledge of the mechanisms by which phagocytes accomplish this function and the ways in which these mechanisms can be deranged, however, has been obtained in the past several years. The neutrophil, in particular, has been the subject of extensive investigation, which has yielded a mass of complex and sometimes conflicting data. In this paper, I review some of the important ways in which impairment of neutrophil function can lead to increased susceptibility to infection.

General properties of mature neutrophils

Some of the important structural features of the mature neutrophil are illustrated in Figure 1. This is an electron micrograph of a cell which has been subjected to a cytochemical technique, so that intracellular sites of peroxidase activity are marked by a dense black reaction product. The cytoplasm of the cell contains numerous granules, which first were shown to be lysosomes by Cohn and Hirsch.1 It now is known that there are at least two distinct types of granules, differing both in morphologic appearance and in the nature of the enzymes and other substances within them. The primary or azurophilic granules are formed only during the promyelocyte stage of neutrophil development,2 and are present in relatively small numbers in the mature neutrophil. These granules, which qualify as lysosomes by virtue of their content of acid hydrolytic enzymes, also contain myeloperoxidase, a variety of basic proteins. . .



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