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The signalling lymphocyte activation molecule family (SLAMF) is a group of cell surface receptors that modulates the activation and differentiation of a wide array of cell types involved in both innate and adaptive immune responses. [1] [2]
In immunology, an antigen (Ag) is any molecule, molecular structure, foreign particulate matter, or pollen grain that can bind to a specific antibody or T-cell receptor. The presence of antigens in the body may trigger an immune response. Antigens can be proteins, peptides, polysaccharides, lipids, or nucleic acids.
The immune system is a network of biological processes that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to parasitic worms, as well as cancer cells and objects such as wood splinters, distinguishing them from the organism's own healthy tissue. Many species have two major subsystems of the immune system. The innate immune system provides a preconfigured response to broad groups of situations and stimuli. The adaptive immune system provides a tailored response to each stimulus by learning to recognize molecules it has previously encountered. Both use molecules and cells to perform their functions.
T cells are one of the important types of white blood cells of the immune system and play a central role in the adaptive immune response. T cells can be distinguished from other lymphocytes by the presence of a T-cell receptor (TCR) on their cell surface.
Toll-like receptors (TLRs) are a class of proteins that play a key role in the innate immune system. They are single-pass membrane-spanning receptors usually expressed on sentinel cells such as macrophages and dendritic cells, that recognize structurally conserved molecules derived from microbes. Once these microbes have reached physical barriers such as the skin or intestinal tract mucosa, they are recognized by TLRs, which activate immune cell responses. The TLRs include TLR1, TLR2, TLR3, TLR4, TLR5, TLR6, TLR7, TLR8, TLR9, TLR10, TLR11, TLR12, and TLR13. Humans lack genes for TLR11, TLR12 and TLR13 and mice lack a functional gene for TLR10. TLR1, TLR2, TLR4, TLR5, TLR6, and TLR10 are located on the cell membrane, whereas TLR3, TLR7, TLR8, and TLR9 are located in intracellular vesicles.
Opsonins are extracellular proteins that, when bound to substances or cells, induce phagocytes to phagocytose the substances or cells with the opsonins bound. Thus, opsonins act as tags to label things in the body that should be phagocytosed by phagocytes. Different types of things ("targets") can be tagged by opsonins for phagocytosis, including: pathogens, cancer cells, aged cells, dead or dying cells, excess synapses, or protein aggregates. Opsonins help clear pathogens, as well as dead, dying and diseased cells.
The adaptive immune system, also known as the acquired immune system, is a subsystem of the immune system that is composed of specialized, systemic cells and processes that eliminate pathogens or prevent their growth. The acquired immune system is one of the two main immunity strategies found in vertebrates.
Pattern recognition receptors (PRRs) play a crucial role in the proper function of the innate immune system. PRRs are germline-encoded host sensors, which detect molecules typical for the pathogens. They are proteins expressed, mainly, by cells of the innate immune system, such as dendritic cells, macrophages, monocytes, neutrophils and epithelial cells, to identify two classes of molecules: pathogen-associated molecular patterns (PAMPs), which are associated with microbial pathogens, and damage-associated molecular patterns (DAMPs), which are associated with components of host's cells that are released during cell damage or death. They are also called primitive pattern recognition receptors because they evolved before other parts of the immune system, particularly before adaptive immunity. PRRs also mediate the initiation of antigen-specific adaptive immune response and release of inflammatory cytokines.
Gut-associated lymphoid tissue (GALT) is a component of the mucosa-associated lymphoid tissue (MALT) which works in the immune system to protect the body from invasion in the gut.
Chemokine ligand 18 (CCL18) is a small cytokine belonging to the CC chemokine family. The functions of CCL18 have been well studied in laboratory settings, however the physiological effects of the molecule in living organisms have been difficult to characterize because there is no similar protein in rodents that can be studied. The receptor for CCL18 has been identified in humans only recently, which will help scientists understand the molecule's role in the body.
A complement receptor is a membrane-bound receptor belonging to the complement system, which is part of the innate immune system. Complement receptors bind effector protein fragments that are produced in response to antigen-antibody complexes or damage-associated molecules. Complement receptor activation contributes to the regulation of inflammation, leukocyte extravasation, and phagocytosis; it also contributes to the adaptive immune response. Different complement receptors can participate in either the classical complement pathway, the alternative complement pathway, or both.
Gamma delta T cells are T cells that have a γδ T-cell receptor (TCR) on their surface. Most T cells are αβ T cells with TCR composed of two glycoprotein chains called α (alpha) and β (beta) TCR chains. In contrast, γδ T cells have a TCR that is made up of one γ (gamma) chain and one δ (delta) chain. This group of T cells is usually less common than αβ T cells, but are at their highest abundance in the gut mucosa, within a population of lymphocytes known as intraepithelial lymphocytes (IELs).
CD244 is a human protein encoded by the CD244 gene. It is also known as Natural Killer Cell Receptor 2B4
Signaling lymphocytic activation molecule 1 is a protein that in humans is encoded by the SLAMF1 gene. Recently SLAMF1 has also been designated CD150.
SLAM family member 6 is a protein that in humans is encoded by the SLAMF6 gene.
Signaling lymphocytic activation molecule (SLAM) is a family of genes. Homophilic binding between SLAMs is involved in cell-to-cell adhesion during antigen presentation.
The nucleotide-binding oligomerization domain-like receptors, or NOD-like receptors (NLRs), are intracellular sensors of pathogen-associated molecular patterns (PAMPs) that enter the cell via phagocytosis or pores, and damage-associated molecular patterns (DAMPs) that are associated with cell stress. They are types of pattern recognition receptors (PRRs), and play key roles in the regulation of innate immune response. NLRs can cooperate with toll-like receptors (TLRs) and regulate inflammatory and apoptotic response. They are found in lymphocytes, macrophages, dendritic cells and also in non-immune cells, for example in epithelium. NLRs are highly conserved through evolution. Their homologs have been discovered in many different animal species (APAF1) and also in the plant kingdom.
Damage-associated molecular patterns (DAMPs) are molecules within cells that are a component of the innate immune response released from damaged or dying cells due to trauma or an infection by a pathogen. They are also known as danger signals, and alarmin because they serve as a warning sign for the organism to alert it of any damage or infection to its cells. DAMPs are endogenous danger signals that are discharged to the extracellular space in response to damage to the cell from mechanical trauma or a pathogen. Once a DAMP is released from the cell, it promotes a noninfectious inflammatory response by binding to a pattern-recognition receptor. Inflammation is a key aspect of the innate immune response; it is used to help mitigate future damage to the organism by removing harmful invaders from the affected area and start the healing process. As an example, the cytokine IL-1α is a DAMP that originates within the nucleus of the cell which, once released to the extracellular space, binds to the PRR IL-1R, which in turn initiates an inflammatory response to the trauma or pathogen that initiated the release of IL-1α. In contrast to the noninfectious inflammatory response produced by DAMPs, pathogen-associated molecular patterns initiate and perpetuate the infectious pathogen-induced inflammatory response. Many DAMPs are nuclear or cytosolic proteins with defined intracellular function that are released outside the cell following tissue injury. This displacement from the intracellular space to the extracellular space moves the DAMPs from a reducing to an oxidizing environment, causing their functional denaturation, resulting in their loss of function. Outside of the aforementioned nuclear and cytosolic DAMPs, there are other DAMPs originated from different sources, such as mitochondria, granules, the extracellular matrix, the endoplasmic reticulum, and the plasma membrane.
The immunochemistry of Triticeae glutens is important in several inflammatory diseases. It can be subdivided into innate responses, class II mediated presentation, class I mediated stimulation of killer cells, and antibody recognition. The responses to gluten proteins and polypeptide regions differs according to the type of gluten sensitivity. The response is also dependent on the genetic makeup of the human leukocyte antigen genes. In gluten sensitive enteropathy, there are four types of recognition, innate immunity, HLA-DQ, and antibody recognition of gliadin and transglutaminase. With idiopathic gluten sensitivity only antibody recognition to gliadin has been resolved. In wheat allergy, the response pathways are mediated through IgE against other wheat proteins and other forms of gliadin.
Innate lymphoid cells (ILCs) are the most recently discovered family of innate immune cells, derived from common lymphoid progenitors (CLPs). In response to pathogenic tissue damage, ILCs contribute to immunity via the secretion of signalling molecules, and the regulation of both innate and adaptive immune cells. ILCs are primarily tissue resident cells, found in both lymphoid, and non- lymphoid tissues, and rarely in the blood. They are particularly abundant at mucosal surfaces, playing a key role in mucosal immunity and homeostasis. Characteristics allowing their differentiation from other immune cells include the regular lymphoid morphology, absence of rearranged antigen receptors found on T cells and B cells, and phenotypic markers usually present on myeloid or dendritic cells.
Skin immunity is a property of skin that allows it to resist infections from pathogens. In addition to providing a passive physical barrier against infection, the skin also contains elements of the innate and adaptive immune systems which allows it to actively fight infections. Hence the skin provides defense in depth against infection.
Cabinian, A; Sinsimer, D; Tang, M; Jang, Y; Choi, B; Laouar, Y; Laouar, A (May 2018). "Gut symbiotic microbes imprint intestinal immune cells with the innate receptor SLAMF4 which contributes to gut immune protection against enteric pathogens". Gut. 67 (5): 847–859. doi:10.1136/gutjnl-2016-313214. PMC 5890651 . PMID 28341747.
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