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Any one of the hepatitis B antigens found on the surface of the Dane particle and on the 20 nm spherical and tubular particles. Several subspecificities of the surface antigen are known. These were formerly called the Australia antigen.
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Produced by B-cells, human immunodeficiency virus (HIV) antibodies reacts with HIV antigens. HIV is a virus which affects white blood cells and eventually destroys the body's natural ability to fight infections.
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An immunoglobulin isotype (subclass). This isotype has the unique ability to bind with high affinity to IgE receptors (FceRI) on mast cells and basophils and induce degranulation and cytokine production by these cells when they are crosslinked by antigen. In addition to a central role in atopy and allergic responses, it has been speculated that IgE-mediated mast cell degranulation, by its release of mediators that increase vascular permeability, has an important role in the initiation of immune response in general.
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The most abundant immunoglobulin G (IgG) subclass in the circulation of healthy individuals. The IgG1 core hinge sequence contains 15 amino acids and two interchain disulfide bonds. This subtype has high affinity for binding both Fc receptors and complement component C1q. IgG1 is the predominant antibody subclass that responds to antigens derived from both soluble and membrane proteins. Reduced levels of circulating IgG1 can indicate the presence of a variety of primary and secondary antibody deficiencies, which can result in hypogammaglobulinemia.
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Along with the immunoglobulin G4 subclass (IgG4), the IgG3 subtype makes up a minor part of circulating antibodies in healthy individuals. The core hinge sequence contains approximately four times the number of amino acids as the other subclasses; allotypes of IgG3 can have up to 62 hinge residues and up to four interchain disulfide bonds. The increased hinge size for IgG3 increases the separation between the Fc (constant fragment) tail and Fab (antigen binding fragment) arms of antibodies of this subclass. This enhances the relative flexibility of the molecule, which may modulate antigen-binding capacity and immune complex formation, and may increase the affinity for binding to both Fc receptors and complement component C1q.
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Along with the immunoglobulin G3 subclass (IgG3), the IgG4 subtype makes up a minor part of circulating antibodies in healthy individuals. The IgG4 core hinge sequence contains 12 amino acids and two interchain disulfide bonds.This subtype has moderate affinity for binding Fc receptors and does not bind complement component C1q. The production of IgG4 can be stimulated following repeated or long-term exposure to antigen. Elevated levels are found in various diseases and infections and can be indicative of an fibroinflammatory syndrome known as IgG4-related disease.
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Prostate-specific antigen — a prostate tissue protein whose blood level rises in prostate cancer and in common benign conditions.
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Soluble monocyte differentiation antigen CD14 is encoded by the human CD14 gene. This soluble protein may be used as a marker of monocyte activation and is derived either through cleavage that removes the glycophosphoinositol (GPI)-anchor from the membrane bound form of CD14 or as non-cleaved form secreted from the non-GPI-modified intracellular pool of CD14.
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A secreted antigen derived from two nearly identical cytoplasmic glycoproteins of the serpin family, serpin B3 (SCCA-1) and serpin B4 (SCCA-2). These proteins are specifically expressed in normal squamous epithelia and are present at elevated concentrations in the serum of subjects with squamous cell carcinoma and certain inflammatory and autoimmune diseases. This antigen was first described in squamous cell cervical carcinoma; it is currently used as a nonspecific tumor marker for the presence, staging and monitoring of the disease course for squamous cell carcinomas of the head and neck, cervix, esophagus, anus and lung.
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Tumor-associated oncofetal glycoprotein 72 (TAG-72) is a high molecular weight (220-400 kD) complex expressed by a wide variety of human adenocarcinomas. This antigen is expressed by a majority of invasive ductal breast carcinomas, and most colon, pancreatic, gastric, esophageal, lung (non-small cell), ovarian and endometrial adenocarcinomas, and on normal secretory endometrium, but not on other normal tissues. It is not expressed by leukemias, lymphomas, sarcomas, mesotheliomas, melanomas or benign tumors. The monoclonal antibodies against TAG-72 have been widely employed for the immunohistochemical analysis of adenocarcinomas as well as for radioimmunoscintigraphy and radioimmunoguided surgery.
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von Willebrand factor (2813 aa, ~309 kDa) is encoded by the human VWF gene. This protein is involved in platelet adhesion and blood coagulation.
