The MacrophageThe ubiquitous phagocytic cells that we know as macrophages vary in many of their characteristics, depending on their location, physiological state, and function. Although Metchnikoff appreciated many of their potentialities nearly a century ago, most early investigators regarded macrophages primarily as scavenger cells. Research in many fields has made it increasingly obvious that macrophages do, in fact, have a multitude of important functions above and beyond their ability to scavenge and dispose of effete cells and extraneous matter. Several decades ago it was realized that macrophages are the chief agents of antimicrobial cellular immunity. Only during the past few years has the importance of the macrophage-cytophilic antibody system in cellular immunity been appreciated. The maturation of monocytes to macrophages, then to epithelioid cells, and finally to giant cells, has been described both in vivo and in vitro. The contribution of this sequence of events to cellular immunity is not fully apparent but is of great interest. Recent research has led to an awareness of the extensive synthetic capabilities of macrophages. It has been shown that these cells can synthesize interferon, components of complement, and numerous other biologically active substances, including a wide array of enzymes. Macrophages are important in allograft rejection. They function in delayed sensitivity reactions and in the pathogenesis of autoimmune diseases. They are probably often essential to antibody formation by their activities of trapping and processing antigen, and perhaps by virtue of the activity of their ribonucleic acid. In addition, macrophages are able to detoxify both exotoxins and endotoxins, as well as other injurious compounds. Thus, macrophages have emerged from their historical role as simple scavenger cells to take their place, with lymphocytes, as mobile cells with a wide spectrum of functions of primary importance to body economy. The possible relationships between macrophages and lymphocytes, and between macrophages and other cell types, remain controversial. However, it is probable that one vital function of macrophages is to regulate the proliferation and differentiation of other cell types, and, conversely, that other cells contribute to macrophage homeostasis. Recent rapid advances in research concerning macrophages have resulted in a tremendous increase in the literature, scattered throughout a wide variety of publications. The object of preparing this monograph is twofold: first, to consolidate available information in order to provide a comprehensive characterization of the macrophage for those unfamiliar with it; and, second, to review some of the most recent work in this area for the benefit of those who are already familiar with the field. Wherever possible, reviews are quoted. Many recent findings, not summarized elsewhere, are reviewed in detail. It is hoped that the references cited will provide a point of departure for gaining further information on subjects of special interest to the reader. Even though much is known about the macrophage and its functions, many problems of great interest remain unsolved. For example, consideration of the control mechanisms which operate in the proliferation and differentiation of macrophages offers a challenge for future research. In addition, the molecular events concerned in macrophage-cytophilic antibody activity are of the utmost importance and are incompletely understood. These and similar problems provide promising areas for further investigation. |
Contents
Introduction | 1 |
The Phylogeny and Ontogeny of Macrophages | 17 |
Macrophages and Cellular Homeostasis | 31 |
Copyright | |
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Common terms and phrases
acid phosphatase allograft alveolar macrophages animals anti antibody formation antibody production antibody response antigen antimicrobial cellular immunity bacteria Benacerraf Biol blast transformation blood Boyden cellular immunity Cohn contribute cultures cytophilic antibodies cytophilic for macrophages cytoplasm delayed sensitivity reactions demonstrated diseases effect effector cells endotoxins enzymes epithelioid cells erythrocytes esterase evidence exudate cells factors function graft granulomatous guinea pig immune macrophages immune response Immunol immunological induced infection ingested inhibition interferon intracellular leprae lepromin lesions lipids lung lymph nodes lymphocytes lymphoid lysosomes Mackaness macro macrophage activity mechanisms membrane metabolism mice migration mitosis monocytes mononuclear mouse Myrvik nonspecific normal observed opsonins organisms parasites particles passive transfer patients peritoneal macrophages phages phagocytic phagocytosis phagosomes pinocytosis PMNs produced proliferation protein rabbits receptors reticuloendothelial reviewed role rophages serum skin specific spleen SRBCs stimulation studies substances synthesis target cells tion tissue trypsin tubercle bacilli tuberculin tuberculosis tumor vitro vivo Weiser x-irradiation