in diabetic patient , periodontium affected by which cells:
- Neutrophil
- Macrophages
Macrophages are cells that belong to the white blood cells, which infiltrate the tissues. They come from the differentiation of circulating blood leukocytes, monocytes. Monocytes and macrophages are phagocytes and are therefore capable of phagocytosis.
They participate in innate immunity as a nonspecific defense, but are able to participate in adaptive immunity via the phenomenon of opsonization. Their role is to phagocyte cell debris and pathogens. Like dendritic cells, they are able to behave like antigen presenting cells. They are large rounded cells with an eccentric nucleus and vacuoles in their cytoplasm.
They were discovered by the Russian biologist Elie Metchnikoff in 1883. Their name comes from the Greek: "big eater", μάκρος, makros = big and φαγεῖν, phagein = eat.
Life cycle:
Macrophages are differentiated from monocytes, which are blood phagocytes, themselves derived from the bone marrow. When a monocyte infiltrates a tissue by crossing the vascular endothelium by diapedesis, it undergoes its terminal differentiation to become a macrophage. Monocytes, then macrophages are attracted to the site of inflammation by chemotaxis. The call signals consist of different stimuli, derived from damaged cells (by necrosis or apoptosis), pathogens, and products released by the cells present at the site: the histamine released by mast cells and basophilic granulocytes, and chemokines and cytokines released by macrophages.
Unlike neutrophil granulocytes, which are the phagocytic cells that are present faster than inflammation and live only a few days, the life span of a macrophage ranges from several months to years. Like most fully differentiated cells, they do not divide.
phagocytosis:
One of the major roles of macrophages is the cleansing of necrotic bodies and apoptotic bodies, debris and dust in the case of the lungs. Elimination of dead cells is important in the early stages of chronic inflammation. This elimination is dominated by the action of neutrophil granulocytes, which will themselves be phagocytosed by macrophages once aged (see CD31 for more details).
Elimination of dust and necrotic tissue is managed on a larger scale (excluding inflammation) by resident macrophages that remain at strategic locations such as the lungs, liver, nerve tissue, bones, spleen and connective tissues, which digest foreign particles such as dust and debris, but also pathogens, recruiting circulating monocytes as needed for their local differentiation into tissue macrophages.
When a macrophage ingests a pathogen, the intracellular vesicle formed is called a phagosome. She will merge with a lysosome. Lysosomal enzymes and free radicals of oxygen (including hypochlorite) will kill and digest the intruder. However, some organisms can resist this process and survive in the macrophage, such as Mycobacterium tuberculosis or Leishmania. A macrophage can digest a hundred bacteria before succumbing to its own digestive enzymes.
Role in adaptive immunity:
After digesting a pathogen, a macrophage may behave as an antigen presenting cell, i.e., present an antigen so as to stimulate a specific T cell. Lymphocyte stimulation by a macrophage is less than that induced by a dendritic cell, but macrophages are able to present antigens associated with molecules of the major class II histocompatibility complex, and thus to stimulate CD4 + lymphocytes.
Immunization also results in the production of antibodies directed against the immunizing antigens. These antibodies will bind to the surface antigens of pathogens. Some isotypes are opsonizing, that is to say that there exist on the phagocytes receptors specific for the constant fragments of the heavy chains of the antibodies. (In the case of IgG (isotype G immunoglobulin), these are CD16, CD32 and CD64.) Macrophages have this type of receptor and the binding of an immune complex to these receptors triggers phagocytosis. Thus, a pathogen that will be invisible to the eyes of a macrophage will become visible once opsonized.
Macrophages are cells that belong to the white blood cells, which infiltrate the tissues. They come from the differentiation of circulating blood leukocytes, monocytes. Monocytes and macrophages are phagocytes and are therefore capable of phagocytosis.
They participate in innate immunity as a nonspecific defense, but are able to participate in adaptive immunity via the phenomenon of opsonization. Their role is to phagocyte cell debris and pathogens. Like dendritic cells, they are able to behave like antigen presenting cells. They are large rounded cells with an eccentric nucleus and vacuoles in their cytoplasm.
They were discovered by the Russian biologist Elie Metchnikoff in 1883. Their name comes from the Greek: "big eater", μάκρος, makros = big and φαγεῖν, phagein = eat.
Life cycle:
Macrophages are differentiated from monocytes, which are blood phagocytes, themselves derived from the bone marrow. When a monocyte infiltrates a tissue by crossing the vascular endothelium by diapedesis, it undergoes its terminal differentiation to become a macrophage. Monocytes, then macrophages are attracted to the site of inflammation by chemotaxis. The call signals consist of different stimuli, derived from damaged cells (by necrosis or apoptosis), pathogens, and products released by the cells present at the site: the histamine released by mast cells and basophilic granulocytes, and chemokines and cytokines released by macrophages.
Unlike neutrophil granulocytes, which are the phagocytic cells that are present faster than inflammation and live only a few days, the life span of a macrophage ranges from several months to years. Like most fully differentiated cells, they do not divide.
phagocytosis:
One of the major roles of macrophages is the cleansing of necrotic bodies and apoptotic bodies, debris and dust in the case of the lungs. Elimination of dead cells is important in the early stages of chronic inflammation. This elimination is dominated by the action of neutrophil granulocytes, which will themselves be phagocytosed by macrophages once aged (see CD31 for more details).
Elimination of dust and necrotic tissue is managed on a larger scale (excluding inflammation) by resident macrophages that remain at strategic locations such as the lungs, liver, nerve tissue, bones, spleen and connective tissues, which digest foreign particles such as dust and debris, but also pathogens, recruiting circulating monocytes as needed for their local differentiation into tissue macrophages.
When a macrophage ingests a pathogen, the intracellular vesicle formed is called a phagosome. She will merge with a lysosome. Lysosomal enzymes and free radicals of oxygen (including hypochlorite) will kill and digest the intruder. However, some organisms can resist this process and survive in the macrophage, such as Mycobacterium tuberculosis or Leishmania. A macrophage can digest a hundred bacteria before succumbing to its own digestive enzymes.
Role in adaptive immunity:
After digesting a pathogen, a macrophage may behave as an antigen presenting cell, i.e., present an antigen so as to stimulate a specific T cell. Lymphocyte stimulation by a macrophage is less than that induced by a dendritic cell, but macrophages are able to present antigens associated with molecules of the major class II histocompatibility complex, and thus to stimulate CD4 + lymphocytes.
Immunization also results in the production of antibodies directed against the immunizing antigens. These antibodies will bind to the surface antigens of pathogens. Some isotypes are opsonizing, that is to say that there exist on the phagocytes receptors specific for the constant fragments of the heavy chains of the antibodies. (In the case of IgG (isotype G immunoglobulin), these are CD16, CD32 and CD64.) Macrophages have this type of receptor and the binding of an immune complex to these receptors triggers phagocytosis. Thus, a pathogen that will be invisible to the eyes of a macrophage will become visible once opsonized.
Involvement in human pathology:
Macrophages participate in certain pathological phenomena, including:
- Macrophages are able to store abnormal lipids. They constitute atherosclerotic plaques and are then called foam cells.
- Macrophages express the CD4 and CCR5 molecules, making them infectable by macrotropic strains of HIV. In practice, HIV infection during sexual contamination passes through macrophages.
- Formation of inflammatory granuloma depends on macrophages.
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