Introduction
Shayne C. Gad in Toxicology of the Gastrointestinal Tract, 2018
The water in saliva provides a medium for dissolving foods so that they can be tasted and digestive reactions can begin. Chloride ions in the saliva activate salivary amylase. Bicarbonate and phosphate ions buffer acidic foods that enter the mouth; as a result, saliva is only slightly acidic (pH 6.35–6.85). Urea and uric acid are found in saliva because salivary glands (like the sweat glands of the skin) help remove waste molecules from the body. Mucus lubricates the food so it can easily be moved about in the mouth, formed into a ball, and swallowed. Immunoglobulin A (IgA) is a secreted type of antibody that prevents attachment of microbes so they cannot penetrate the epithelium. The enzyme lysozyme kills bacteria. Even though these substances help protect the mucous membrane from infection and the teeth from decay, they are not present in large enough quantities to eliminate all oral bacteria.
Pulmonary Immunology
Lourdes R. Laraya-Cuasay, Walter T. Hughes in Interstitial Lung Diseases in Children, 2019
The five major classes of immunoglobulins have different functional characteristics. IgG is the immunoglobulin primarily involved in the secondary or recall immune response. The ability of IgG to diffuse into tissues facilitates combination with and elimination of antigens. IgM is the major early antibody, its molecule consists of five subunits that are linked by disulfide bonds and a J chain. Although it is incapable of placental transfer its polymeric structure produces efficient agglutination or destruction of the antigen. IgA is the primary immunoglobulin of all mucosal surfaces and respiratory secretions. It exists either as a monomer or dimer. Secretory IgA is eqipped with a polypeptide (a secretory piece) that provides relative protection from enzymatic digestion at the mucosal level. IgD is an immunoglobulin present in very small quantities in the serum and its functional role awaits further definition. IgE is also called the reagenic antibody; though present in small concentrations it has an important role in atopic disorders.
Transforming Growth Factor-β: A Cytokine Paradigm
Thomas F. Kresina in Immune Modulating Agents, 2020
While tolerance can be induced by several mechanisms, early studies found that by feeding a protein and then subsequently challenging with that protein, a state of systemic hyporesponsiveness to the protein is created [46]. In an attempt to provide a more focused, and ideally a less toxic, treatment than is presently offered by current immunosuppressive drugs, tolerance induction via oral ingestion has been extensively exploited in the last decade. While the actual mechanism(s) behind oral tolerance induction is not completely understood, TGF-β is considered to play a key role [46]. After ingestion, antigen is taken up and delivered to the gut-associated lymphoid tissue (GALT), which includes Peyer’s patches and intraepithelial lymphocytes, for antigen processing. Antigenic stimulation leads to a change in the cytokine secretion profile by GALT lymphocyte populations. Production of Th1 cytokines, such as IL-2 and IFN-γ, is down-regulated, whereas Th2 cytokines, such as IL-4 and IL-10 as well as TGF-β, are up-regulated (Figure 1) [47]. Release of TGF-β1 by T cells is dependent upon antigen-specific triggering by the oral toleragen. As previously mentioned, local secretion of TGF-β1 within the GALT aids in IgA class switching by resident B cells. Immunoglobulin A is essential for the clearance of orally ingested antigens (food), preventing the development of deleterious inflammatory responses within the gut.
Antibody tests for COVID-19
Published in Baylor University Medical Center Proceedings, 2021
Jonathan Kopel, Hemant Goyal, Abhilash Perisetti
Antibody tests detect the presence of antibodies produced by B cells toward a specific pathogen.8 The activation and differentiation of B cells into antibody-secreting plasma cells are initiated through antigen-presenting cells (e.g., dendritic cells, macrophages, helper T cells). The body produces two major types of antibodies, immunoglobulin M (IgM) and immunoglobulin G (IgG), in response to an infection.8 The IgM antibodies are produced soon after infection, while the IgG antibodies are produced later to maintain the body’s immune system to the same infection.8,9 The third type of immunoglobulin, known as IgA, is found on mucous membranes and aids the innate immune response.9–11 Current clinical reports show that antibodies against SARS-CoV-2 viral particles develop between 6 and 10 days after infection, with peak IgM antibody levels at 12 days, and persist for 35 days. In contrast, the IgG antibodies peak around 17 days and persist for up to 49 days.9–11 Serological or antibody tests detect immunoglobulins produced in the presence of antigens from SARS-CoV-2.
Maternal sucralose intake alters gut microbiota of offspring and exacerbates hepatic steatosis in adulthood
Published in Gut Microbes, 2020
Xin Dai, Zixuan Guo, Danfeng Chen, Lu Li, Xueli Song, Tianyu Liu, Ge Jin, Yun Li, Yi Liu, Aihemaiti Ajiguli, Cheng Yang, Bangmao Wang, Hailong Cao
The tight junction proteins including ZO-1, Claudin-1, Claudin-3, and Occludin are considered as the most important factors in determining the integrity of gut barrier.16According to polymerase chain reaction (PCR) data, the expression of Claudin-1, Claudin-3, and ZO-1 significantly decreased in MS group, while that of Occludin was similar in the two groups (Figure 3a). Besides, immunofluorescence also suggested that the expression of ZO-1 protein decreased in MS group (Figure 3b). Immunoglobulin A (IgA), functioning as inhibiting pathogens from adhering to the mucous, plays a critical role in the gut immunological barrier function.15As immunofluorescence of IgA showed, MS dramatically decreased the level of IgA expression in the small intestine (Figure 3c–d). These data indicate that MS can inhibit intestinal development and disrupt the integrity of gut barrier in early life of offspring.
In vivo immunogenicity of bovine bone removed by a novel decellularization protocol based on supercritical carbon dioxide
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2018
Ling You, Xu Weikang, Yang Lifeng, Liang Changyan, Lin Yongliang, Wei Xiaohui, Xu Bin
Immunoglobulin is secreted by B lymphocyte, which is used to identify and neutralize foreign substances by the immune system. The mice were implanted after 7 and 14 days, the kappa and lambda chain contents of IgM, IgA, IgG3, IgG2a and IgG1 in peripheral blood of BB group were significantly higher than the others. The result of DBB group was similar with MC1 and MC2 group. At 28 day, the contents of IgMκ, IgMλ, IgG1κ, IgG1λ, IgG2aκ and IgG3κ of BB group was significantly higher than the others. The contents of IgAκ, IgAλ, IgG2aλ, and IgG3λ was also higher than the others, but without significant difference (Figures 9 and 10). This might because the intensity of mice’s immune rejection against the implants was less after 28 days, which agree with the results of a number of macrophages and neutrophils, in vitro splenocyte proliferation and cytokine profiles. Whatever, the immune response of DBB group was weaker than the BB group.
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