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Defects in apoptotic cell clearance is usually associated with impaired phagocytosis of macrophages. Accumulation of apoptotic cell remnants often causes autoimmune disorders; thus pharmacological potentiation of phagocytosis has a medical potential in treatment of certain forms of autoimmune disorders. [21] [22] [23] [24]
Macrophages are the predominant cells involved in creating the progressive plaque lesions of atherosclerosis. [89] Focal recruitment of macrophages occurs after the onset of acute myocardial infarction. These macrophages function to remove debris, apoptotic cells and to prepare for tissue regeneration. [90]
Phagoptosis has multiple functions including removal and disposal of: pathogenic cells, aged cells, damaged cells, stressed cells and activated cells. Pathogenic cells such as bacteria can be opsonised by antibodies or complement factors, enabling their phagocytosis and phagoptosis by macrophages and neutrophils.
Apoptosis is a form of programmed cell death that is used by the body to remove unwanted, damaged, or senescent cells from tissues. Removal of apoptotic cells is carried out via phagocytosis by white blood cells such as macrophages and dendritic cells.
In cell biology, a phagosome is a vesicle formed around a particle engulfed by a phagocyte via phagocytosis. Professional phagocytes include macrophages, neutrophils, and dendritic cells (DCs). [1] A phagosome is formed by the fusion of the cell membrane around a microorganism, a senescent cell or an apoptotic cell.
In both cases C1q activates complement, resulting in the cells being marked for phagocytosis by C3b and C4b. C1q is an important contributor to the clearance of apoptotic cells and debris. This process usually occurs in late apoptotic cells. [6] Opsonization of apoptotic cells occurs by different mechanisms in a tissue-dependent pattern.
Dendritic cells and macrophages are not so fast, and phagocytosis can take many hours in these cells. Macrophages are slow and untidy eaters; they engulf huge quantities of material and frequently release some undigested back into the tissues. This debris serves as a signal to recruit more phagocytes from the blood. [27]
Efferocytosis can be performed not only by 'professional' phagocytic cells such as macrophages or dendritic cells, but also by many other cell types including epithelial cells and fibroblasts. To distinguish them from living cells, apoptotic cells carry specific 'eat me' signals, such as the presence of phosphatidyl serine (resulting from ...