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Donor-specific Antibody
Donor-specific antibodies (DSA) are a concept in transplantation medicine and describe the presence of antibodies specific to the Donor's HLA-Molecules. These antibodies can cause antibody-mediated rejection and are therefore considered a contraindication against transplantation in most cases.Lionaki S, Panagiotellis K, Iniotaki A, Boletis JN. Incidence and clinical significance of de novo donor specific antibodies after kidney transplantation. Clin Dev Immunol. 2013; 2013:849835. DSA are a result of B cell and plasma cell activation and bind to HLA and/or non-HLA molecules on the endothelium of the graft. They were first described in 1969 by Patel et al., who found that Transplant recipients who were positively tested for DSA using a complement-dependent cytotoxicity crossmatch assay had a higher risk of transplant rejection.Patel R, Terasaki PI. Significance of the positive crossmatch test in kidney transplantation. N Engl J Med. 1969; 280(14):735-9. DSA can either be pre-formed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
B Cell
B cells, also known as B lymphocytes, are a type of white blood cell of the lymphocyte subtype. They function in the humoral immunity component of the adaptive immune system. B cells produce antibody molecules which may be either secreted or inserted into the plasma membrane where they serve as a part of B-cell receptors. When a naïve or memory B cell is activated by an antigen, it proliferates and differentiates into an antibody-secreting effector cell, known as a plasmablast or plasma cell. Additionally, B cells present antigens (they are also classified as professional antigen-presenting cells (APCs)) and secrete cytokines. In mammals, B cells mature in the bone marrow, which is at the core of most bones. In birds, B cells mature in the bursa of Fabricius, a lymphoid organ where they were first discovered by Chang and Glick, which is why the 'B' stands for bursa and not bone marrow as commonly believed. B cells, unlike the other two classes of lymphocytes, T cells and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plasma Cell
Plasma cells, also called plasma B cells or effector B cells, are white blood cells that originate in the lymphoid organs as B lymphocytes and secrete large quantities of proteins called antibodies in response to being presented specific substances called antigens. These antibodies are transported from the plasma cells by the blood plasma and the lymphatic system to the site of the target antigen (foreign substance), where they initiate its neutralization or destruction. B cells differentiate into plasma cells that produce antibody molecules closely modeled after the receptors of the precursor B cell. Structure Plasma cells are large lymphocytes with abundant cytoplasm and a characteristic appearance on light microscopy. They have basophilic cytoplasm and an eccentric nucleus with heterochromatin in a characteristic cartwheel or clock face arrangement. Their cytoplasm also contains a pale zone that on electron microscopy contains an extensive Golgi apparatus and centrioles ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Human Leukocyte Antigen
The human leukocyte antigen (HLA) system or complex is a complex of genes on chromosome 6 in humans which encode cell-surface proteins responsible for the regulation of the immune system. The HLA system is also known as the human version of the major histocompatibility complex (MHC) found in many animals. Mutations in HLA genes may be linked to autoimmune disease such as type I diabetes, and celiac disease. The HLA gene complex resides on a 3 Mbp stretch within chromosome 6, p-arm at 21.3. HLA genes are highly polymorphic, which means that they have many different alleles, allowing them to fine-tune the adaptive immune system. The proteins encoded by certain genes are also known as ''antigens'', as a result of their historic discovery as factors in organ transplants. HLAs corresponding to MHC class I ( A, B, and C), all of which are the HLA Class1 group, present peptides from inside the cell. For example, if the cell is infected by a virus, the HLA system brings fragme ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endothelium
The endothelium is a single layer of squamous endothelial cells that line the interior surface of blood vessels and lymphatic vessels. The endothelium forms an interface between circulating blood or lymph in the lumen and the rest of the vessel wall. Endothelial cells form the barrier between vessels and tissue and control the flow of substances and fluid into and out of a tissue. Endothelial cells in direct contact with blood are called vascular endothelial cells whereas those in direct contact with lymph are known as lymphatic endothelial cells. Vascular endothelial cells line the entire circulatory system, from the heart to the smallest capillaries. These cells have unique functions that include fluid filtration, such as in the glomerulus of the kidney, blood vessel tone, hemostasis, neutrophil recruitment, and hormone trafficking. Endothelium of the interior surfaces of the heart chambers is called endocardium. An impaired function can lead to serious health issues throug ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cytotoxicity
Cytotoxicity is the quality of being toxic to cells. Examples of toxic agents are an immune cell or some types of venom, e.g. from the puff adder (''Bitis arietans'') or brown recluse spider (''Loxosceles reclusa''). Cell physiology Treating cells with the cytotoxic compound can result in a variety of cell fates. The cells may undergo necrosis, in which they lose membrane integrity and die rapidly as a result of cell lysis. The cells can stop actively growing and dividing (a decrease in cell viability), or the cells can activate a genetic program of controlled cell death (apoptosis). Cells undergoing necrosis typically exhibit rapid swelling, lose membrane integrity, shut down metabolism, and release their contents into the environment. Cells that undergo rapid necrosis in vitro do not have sufficient time or energy to activate apoptotic machinery and will not express apoptotic markers. Apoptosis is characterized by well defined cytological and molecular events including a change i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sommer Gentry
Sommer Elizabeth Gentry is an American mathematician who works as a professor of mathematics at the United States Naval Academy and as a research associate in surgery at the Johns Hopkins School of Medicine. Her research concerns operations research and its applications to the optimization of organ transplants, and has led to the discovery of geographic inequities in organ allocation. She is also interested in dancing, teaches swing dancing at the Naval Academy, and wrote her doctoral dissertation on the mathematics and robotics of dance. Early life and education Gentry is originally from California. As a girl, she was inspired to continue in mathematics by the recreational mathematics columns of Martin Gardner and Ivars Peterson. In 1993, as a senior at Thousand Oaks High School, Gentry had the highest individual score at the Ventura County, California county-level Academic Decathlon. She graduated from Stanford University in 1998, with both a bachelor's degree in mathematical and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Panel Reactive Antibody
A panel-reactive antibody (PRA) is a group of antibodies in a test serum that are reactive against any of several known specific antigens in a panel of test cells or purified HLA antigens from cells. It is an immunologic test routinely performed by clinical laboratories on the blood of people awaiting organ transplantation. In this test recipient cells are exposed to random cells of donor population and estimation risk of acute rejection. The PRA score is expressed as a percentage between 0% and 100%. It represents the proportion of the population to which the person being tested will react via pre-existing antibodies against human cell surface antigens, which include human leukocyte antigen, HLA] and other polymorphic antigen systems. A PRA score greater than 6 is in danger, and over 20 requires a desensitization process, but its intensity varies. These antibodies target the surface antigens of target cells, such as HLAs. In other words, it is a test of the degree of alloimmuni ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organ Donor
Organ donation is the process when a person allows an organ of their own to be removed and transplanted to another person, legally, either by consent while the donor is alive or dead with the assent of the next of kin. Donation may be for research or, more commonly, healthy transplantable organs and tissues may be donated to be transplanted into another person. Common transplantations include kidneys, heart, liver, pancreas, intestines, lungs, bones, bone marrow, skin, and corneas. Some organs and tissues can be donated by living donors, such as a kidney or part of the liver, part of the pancreas, part of the lungs or part of the intestines, but most donations occur after the donor has died. In 2019, Spain had the highest donor rate in the world at 46.91 per million people, followed by the US (36.88 per million), Croatia (34.63 per million), Portugal (33.8 per million), and France (33.25 per million). As of February 2, 2019, there were 120,000 people waiting for life-savin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Autoantibody
An autoantibody is an antibody (a type of protein) produced by the immune system that is directed against one or more of the individual's own proteins. Many autoimmune diseases (notably lupus erythematosus) are associated with such antibodies. Production Antibodies are produced by B cells in two ways: (i) randomly, and (ii) in response to a foreign protein or substance within the body. Initially, one B cell produces one specific kind of antibody. In either case, the B cell is allowed to proliferate or is killed off through a process called clonal deletion. Normally, the immune system is able to recognize and ignore the body's own healthy proteins, cells, and tissues, and to not overreact to non-threatening substances in the environment, such as foods. Sometimes, the immune system ceases to recognize one or more of the body's normal constituents as "self," leading to production of pathological autoantibodies. Autoantibodies may also play a nonpathological role; for instance they m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Titer
Titer (American English) or titre (British English) is a way of expressing concentration. Titer testing employs serial dilution to obtain approximate quantitative information from an analytical procedure that inherently only evaluates as positive or negative. The titre corresponds to the highest dilution factor that still yields a positive reading. For example, positive readings in the first 8 serial, twofold dilutions translate into a titer of 1:256 (i.e., 2−8). Titres are sometimes expressed by the denominator only, for example 1:256 is written 256. The term also has two other, conflicting meanings. In titration, the titer is the ratio of actual to nominal concentration of a titrant, e.g. a titer of 0.5 would require 1/0.5 = 2 times more titrant than nominal. This is to compensate for possible degradation of the titrant solution. Second, in textile engineering, titre is also a synonym for linear density. Etymology Titer has the same origin as the word "title", from the Fren ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Complement Activation
The complement system, also known as complement cascade, is a part of the immune system that enhances (complements) the ability of antibodies and phagocytic Phagocytosis () 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 c ... cells to clear microbes and damaged cells from an organism, promote inflammation, and attack the pathogen's cell membrane. It is part of the innate immune system, which is not adaptable and does not change during an individual's lifetime. The complement system can, however, be recruited and brought into action by antibodies generated by the adaptive immune system. The complement system consists of a number of small proteins that are synthesized by the liver, and circulate in the blood as inactive Protein precursor, precursors. When stimulated by one of several triggers, prote ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kidney Transplantation
Kidney transplant or renal transplant is the organ transplant of a kidney into a patient with end-stage kidney disease (ESRD). Kidney transplant is typically classified as deceased-donor (formerly known as cadaveric) or living-donor transplantation depending on the source of the donor organ. Living-donor kidney transplants are further characterized as genetically related (living-related) or non-related (living-unrelated) transplants, depending on whether a biological relationship exists between the donor and recipient. Before receiving a kidney transplant, a person with ESRD must undergo a thorough medical evaluation to make sure that they are healthy enough to undergo transplant surgery. If they are deemed a good candidate, they can be placed on a waiting list to receive a kidney from a deceased donor. Once they are placed on the waiting list, they can receive a new kidney very quickly, or they may have to wait many years; in the United States, the average waiting time is three t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
