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The activation of T H 1 and M1 macrophage is a positive feedback loop, with IFN-γ from T H 1 cells upregulating CD40 expression on macrophages; the interaction between CD40 on the macrophages and CD40L on T cells activate macrophages to secrete IL-12; and IL-12 promotes more IFN-γ secretion from T H 1 cells.
Phagocytosis (from Ancient Greek φαγεῖν (phagein) 'to eat' and κύτος (kytos) 'cell') is the process by which a cell uses its plasma membrane to engulf a large particle (≥ 0.5 μm), giving rise to an internal compartment called the phagosome. It is one type of endocytosis. A cell that performs phagocytosis is called a phagocyte.
[49] [50] These molecules mark the cell for phagocytosis by cells that possess the appropriate receptors, such as macrophages. [51] The removal of dying cells by phagocytes occurs in an orderly manner without eliciting an inflammatory response and is an important function of phagocytes. [52]
The cells are primarily monocytes and macrophages, and they accumulate in lymph nodes and the spleen. The Kupffer cells of the liver and tissue histiocytes are also part of the MPS. The mononuclear phagocyte system and the monocyte macrophage system refer to two different entities, often mistakenly understood as one. [citation needed]
Phagocytosis of a bacterium, showing the formation of phagosome and phagolysosome. 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]
One type of MHC class II deficiency, also called bare lymphocyte syndrome, is due to mutations in the genes that code for transcription factors that regulate the expression of the MHC class II genes. [16] It results in the depletion of CD4 T cells and some immunoglobulin isotypes even though there are normal levels of both CD8 Cells and B cells ...
An immune complex, sometimes called an antigen-antibody complex or antigen-bound antibody, is a molecule formed from the binding of multiple antigens to antibodies. [1] The bound antigen and antibody act as a unitary object, effectively an antigen of its own with a specific epitope .
Opsonins are extracellular proteins that, when bound to substances or cells, induce phagocytes to phagocytose the substances or cells with the opsonins bound. [1] Thus, opsonins act as tags to label things in the body that should be phagocytosed (i.e. eaten) by phagocytes (cells that specialise in phagocytosis, i.e. cellular eating). [1]