Mononuclear Phagocytes

Methods for Studying Mononuclear Phagocytes is a practical guide to the study of mononuclear phagocytes that brings together various well-established and useful methods for examining these cells. The technical protocols have been made detailed, specific, practical, and inclusive of the necessary mystique for immediate and direct application in the laboratory. The book is divided into 11 parts arranged according to the sequence of steps that would generally be followed to study a given population of mononuclear phagocytes: (I) methods for obtaining and culturing populations of human and animal mononuclear phagocytes; (II) methods for separating populations of leukocytes to enrich or deplete their content of mononuclear phagocytes; (II) criteria and techniques for identifying mononuclear phagocytes; (IV) methods for quantifying the number of mononuclear phagocytes; (V) techniques for studying the morphology of mononuclear phagocytes; (VI) methods for quantifying the biochemical constituents of mononuclear phagocytes; (VII) methods of quantifying phagocytosis, pinocytosis, and chemotaxis; (VIII) methods for quantifying the secretory products of mononuclear phagocytes; (IX) procedures for quantifying the destruction of tumor cells and of microorganisms by mononuclear phagocytes; (X) methods for studying the cell biology of mononuclear phagocytes; and (XI) techniques for studying mononuclear phagocytes in vivo, including procedures for estimating their kinetics, accumulation, identification, and microbicidal properties.

Mononuclear phagocytes, which include macrophages, monocytes and their precursor cells, are the most important cells in the host defence against micro-organisms and tumor cells. During the last twenty-five years research on the biology of mononuclear phagocytes has increased tremendously. This motivated Professor R. van Furth to organize five international conferences on this subject in Leiden, the Netherlands. The edited proceedings of these meethings were published: in 1970 Mononuclear Phagocytes; in 1975 Mononuclear Phagocytes in Immunity, Infections and Pathology; in 1980 Mononuclear Phagocytes -- Functional Aspects; and in 1985 Mononuclear Phagocytes -- Characteristics, Physiology and Function. Reviews of these volumes, published in international journals, praised them as the most up-to-date state of the art publications. The publication of 1991 includes 88 chapters written by more than 200 authors.

Sixteen years have passed since the first Leiden Conference on Mononuclear Phagocytes. That first meeting led to new nomenclature, i. e. , the Mononuclear Phagocytes System (MPS), which was published in the Bulletin of the World Health Organization (R. van Furth, et aI. , Bull. WHO, 1972, 46: 845-852). The paradigm of the MPS has the advantage of being much more consistent than the Reticuloendothelial System (RES) (L. Aschoff, Ergebn. Inn. Med. Kinderheilk. 1924, 26:1), because cells with similar characteristics can be classified in the same category. The essence ota new concept is, according to Popper, that it must be susceptible to falsification. This has been attempted several times for the MPS by those who adhere to the RES. However, in biology no one can be certain of truth. Any theory must be based on experimental observations and/or theoretical consider ations and both should be presented in such a way that others can try to refute it, then or later. One may have a theoretical or a pragmatic preference for a theory which at a given time is regarded as possibly truc, but later it may be shown to be false. In other words, what we present in this volume is regarded as true at this moment, but others may consider it as not true and try to disprove it. Controversies often stimulate new research.

Mononuclear Phagocytes in Cell Biology provides a state-of-the-art review of the biological, biochemical, and molecular processes involved in macrophage activation. The book focuses on the role of macrophage "signals" in health and disease, which are discussed with particular attention to the physiological role of macrophages in homeostasis. The role played by macrophages in bone metabolism and the role of cytokines in diseases affecting the macrophage (e.g., HIV and leishmaniasis) are covered as well. The book also exploits the potential of macrophage "mimicry" as a therapeutic tool. Mononuclear Phagocytes in Cell Biology is a practical reference for cell biologists, medical microbiologists, molecular biologists, immunologists, hematologists, immunogeneticists, immunopharmacologists, and other basic and clinical researchers interested in macrophage development, biology, and differentiation.

The Mononuclear Phagocyte System (MPS) of vertebrates is composed of monocytes, macrophages and dendritic cells. Together, they form part of the first line of immune defense against a variety of pathogens (bacteria, fungi, parasites and viruses), and thus play an important role in maintaining organism homeostasis. The mode of transmission, type of replication and mechanism of disease-causing differ significantly for each pathogen, eliciting a unique immune response in the host. Within this context, the MPS acts as both the sentinel and tailor of the immune system. As sentinels, MPS cells are found in blood and within tissues throughout the body to patrol against pathogenic insult. The strategy to detect 'microbial non-self' relies on MPS to recognize conserved microbial products known as 'pathogen-associated molecular pattern' (PAMPs). PAMPs recognition represents a checkpoint in the response to pathogens and relies on conserved 'pattern recognition receptors' (PRRs). Upon PRR engagement, MPS mount a cell-autonomous attack that includes the internalization and compartmentalization of intracellular pathogens into toxic compartments that promote destruction. In parallel, MPS cells launch an inflammatory response composed of a cellular arm and soluble factors to control extracellular pathogens. In cases when innate immunity fails to eliminate the invading microbe, MPS serves as a tailor to generate adaptive immunity for pathogen eradication and generation of "memory" cells, thus ensuring enhanced protection against re-infection. Indeed, MPS cell functions comprise the capture, process, migration and delivery of antigenic information to lymphoid organs, where type-1 immunity is tailored against intracellular microbes and type-2 immunity against extracellular pathogens. However, this potent adaptive immunity is also a double-edge sword that can cause aberrant inflammatory disorders, like autoimmunity or chronic inflammation. For this reason, MPS also tailors tolerance immunity against unwanted inflammation. Successful clearance of the microbe results in its destruction and proper collection of debris, resolution of inflammation and tissue healing for which MPS is essential. Reciprocally, as part of the evolutionary process taking place in all organisms, microbes evolved strategies to circumvent the actions bestowed by MPS cells. Multiple pathogens modulate the differentiation, maturation and activation programs of the MPS, as an efficient strategy to avoid a dedicated immune response. Among the most common evasion strategies are the subversion of phagocytosis, inhibition of PRR-mediated immunity, resistance to intracellular killing by reactive oxygen and nitrogen species, restriction of phagosome maturation, modulation of cellular metabolism and nutrient acquisition, regulation of cell death and autophagy, and modulation of pro-inflammatory responses and hijacking of tolerance mechanisms, among others. The tenet of this eBook is that a better understanding of MPS in infection will yield insights for development of therapeutics to enhance antimicrobial processes or dampen detrimental inflammation for the host's benefit. We believe that contributions to this topic will serve as a platform for discussion and debate about relevant issues and themes in this field. Our aim is to bring expert junior and senior scientists to address recent progress, highlight critical knowledge gaps, foment scientific exchange, and establish conceptual frameworks for future MPS investigation in the context of infectious disease.