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Category: Microbial Genetics and Molecular Biology
Adaptive Characteristics of Innate Immune Responses in Macrophages, Page 1 of 2
< Previous page | Next page > /docserver/preview/fulltext/10.1128/9781555819194/9781555819187_Chap38-1.gif /docserver/preview/fulltext/10.1128/9781555819194/9781555819187_Chap38-2.gifAbstract:
Macrophages are a central component of antimicrobial host defense, described as being crucial for both innate immune mechanisms and adaptive immunity ( 1 ). The dichotomy between the immediate antimicrobial responses seen as nonspecific and the relatively late-onset specific T- and B-cell responses has driven our understanding of host defense for more than half a century. Innate immunity reacts instantly upon an encounter with a pathogen but has been viewed as nonspecific and incapable of building immunological memory. In contrast, adaptive immune responses can specifically recognize pathogenic microorganisms and build memory capable of protection against reinfection. Macrophages are involved in both of these responses: on the one hand, macrophages have the capacity to phagocytose and kill microorganisms in a nonspecific fashion, as well as to release proinflammatory mediators that drive inflammation; but on the other hand, they can also present antigens and initiate and modulate the specific T-cell responses through expression of costimulatory molecules and specific cytokines ( 2 ).
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Priming, activation, and tolerance as adaptive macrophage responses. A schematic representation of the possible responses of macrophages to a novel stimulus (e.g., LPS). While LPS causes macrophage activation followed by tolerance, low doses of LPS prime macrophages for enhanced innate immune responses: trained innate immunity. Both tolerance and trained innate immunity are results of long-term epigenetic changes in macrophage function (“memory”).
Priming, activation, and tolerance as adaptive macrophage responses. A schematic representation of the possible responses of macrophages to a novel stimulus (e.g., LPS). While LPS causes macrophage activation followed by tolerance, low doses of LPS prime macrophages for enhanced innate immune responses: trained innate immunity. Both tolerance and trained innate immunity are results of long-term epigenetic changes in macrophage function (“memory”).
Macrophages play a double role in inducing immunological memory following an infectious insult: on the one hand, they initiate adaptive immune responses; and on the other hand, they undergo epigenetic reprogramming to respond with an increased array of PRR expression and inflammatory cytokine production to a secondary infection (“trained innate immunity”). MHC, major histocompatibility complex.
Macrophages play a double role in inducing immunological memory following an infectious insult: on the one hand, they initiate adaptive immune responses; and on the other hand, they undergo epigenetic reprogramming to respond with an increased array of PRR expression and inflammatory cytokine production to a secondary infection (“trained innate immunity”). MHC, major histocompatibility complex.
Examples of memory of innate immunity in plants, invertebrates, and mammals a
Examples of memory of innate immunity in plants, invertebrates, and mammals a