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The Inducible System: History of Development of Immunology as a Component of Host-Parasite Interactions
Published in Julius P. Kreier, Infection, Resistance, and Immunity, 2022
Antigen recognition is restricted by self-recognition both for the initiation of an immune response by helper T lymphocytes and for the killing of virally infected cells by cytotoxic lymphocytes. The major histocompatibility complex gene products that restrict antigen recognition by helper lymphocytes (the so-called class II MHC proteins) are different from the products that restrict antigen recognition by cytotoxic lymphocytes (class 1 MHC proteins). Class I MHC proteins are found on the surfaces of all vertebrate cells. Their role is to present antigens arising in the cytoplasm of target cells to cytotoxic T lymphocytes. Typically these are viral antigens displayed by virally infected cells. Class II MHC antigens, however, are only found on the surfaces of antigen presenting cells. Their function is to present antigen taken up by APC through phagocytosis to the helper T cell. The helper T cell then helps trigger a humoral immune response. The selective advantage of two functionally distinct sets of MHC proteins may be to prevent cytotoxic lymphocytes from destroying APCs that are presenting antigen for the initiation of the immune response.
Cellular and Immunobiology
Published in Karl H. Pang, Nadir I. Osman, James W.F. Catto, Christopher R. Chapple, Basic Urological Sciences, 2021
Masood Moghul, Sarah McClelland, Prabhakar Rajan
Types of antibodies include:IgM: first antibody produced by B-cells post-infection; activates complement.IgG: produced second, and yields a much bigger response.IgA: only seen in mucosal sites.IgD: antigen recognition in B-cells.IgE: found on mast cells and involved in allergic responses.
Basics of Allergy
Published in Pudupakkam K Vedanthan, Harold S Nelson, Shripad N Agashe, PA Mahesh, Rohit Katial, Textbook of Allergy for the Clinician, 2021
Rafeul Alam, Dipa K Sheth, Magdalena M Gorska
The immune system is composed of an adaptive immune system and an innate immune system. The adaptive immune system distinguishes itself from the innate system by the following features: (a) Specificity of antigen recognition, (b) Diversity of the antigen receptor repertoire, (c) Rapid clonal expansion, (d) Adaptiveness to the changing environment and (e) Immunological memory. The innate system lacks fine specificity, has limited diversity and rudimentary memory but manifests rapid engagement. Lymphocytes are the primary cells of adaptive immunity; they include T cells, B cells and NK cells. Each individual cell type will be described in this chapter.
Cholangiocarcinoma: what are the most valuable therapeutic targets – cancer-associated fibroblasts, immune cells, or beyond T cells?
Published in Expert Opinion on Therapeutic Targets, 2021
Juan Wang, Emilien Loeuillard, Gregory J. Gores, Sumera I. Ilyas
In contrast to T lymphocytes, the role of B lymphocytes in CCA development and progression is far less clear. B cells have an integral role in humoral immunity via the production of immunoglobulins. Upon antigen recognition, naïve B cells become activated B cells and subsequently differentiate into plasma cells, which are capable of antibody production [86]. There are several subsets of B lymphocytes, including pro-tumor or regulatory B cells that can dampen the antitumor immune response and promote tumorigenesis. In pancreatic ductal adenocarcinoma, IL-35 producing B cells stimulated tumor cell proliferation [87]. This B cell subset was recruited to the tumor by the chemoattractant CXCL-13, and CXCL13 blockade resulted in a decline in this population with reduction of tumor growth [87]. Although these findings imply that B cell–based immunotherapeutic approaches may hold promise, the role of B lymphocytes in CCA has yet to be elucidated.
Chicken toll-like receptors and their significance in immune response and disease resistance
Published in International Reviews of Immunology, 2019
Aamir Nawab, Lilong An, Jiang Wu, Guanghui Li, Wenchao Liu, Yi Zhao, Qimin Wu, Mei Xiao
Generally, a bird’s defense system depends on both specific and nonspecific immune responses towards invading pathogens. Both types of immune responses provide protection by initiating the inflammatory response to eliminate the infectious agents. Specific (adaptive) immunity is found only in the vertebrates which are mediated by B and T cells after identifying danger signals. Conversely, nonspecific (innate) immunity is observed in the vertebrates as well as invertebrates. The mechanism whereby specific immunity recognizes pathogens has been well explained. However, the mechanism for antigen recognition by nonspecific immunity remains unclear. The first Toll gene was discovered in the adult fruit fly (Drosophila melanogaster) which triggered the nonspecific immune response against the fungal infections [1]. One year subsequently, a homolog of Drosophila toll was recognized in mammals termed as Toll-like receptors [2].
Modulating effect of a new ester, 28-O-phosphatidylbetulin (DAPB), obtained from hen egg yolk lecithin and betulin on lymphocyte subsets and humoral immune response in mice
Published in Immunopharmacology and Immunotoxicology, 2019
Magdalena Lis, Barbara Barycza, Angelika Sysak, Aleksandra Pawlak, Agnieszka Suszko-Pawłowska, Marianna Szczypka, Czesław Wawrzeńczyk, Bożena Obmińska-Mrukowicz
Both compounds also affected the humoral immune response in the mice immunized with SRBC. Betulin, but not DAPB, administered four times before the SRBC injection enhanced the number of cells producing anti-SRBC antibodies (PFC). The level of total (IgM + IgG) hemagglutinin rose also in the animals treated with both doses of betulin before the immunization. While four exposures to 10 mg/kg of betulin after priming increased the production of total and 2-mercaptoethanol resistant (IgG) hemagglutinin. IgG is the most abundant class of antibodies in serum, and IgM is the first immunoglobulin class produced in a primary response to an antigen. The adaptive immune response is based on antigen recognition and presentation, specific T- and B-cells activation and proliferation, and antibody synthesis by B-cells. Unlike betulin, DAPB exerted only a little impact on the production of anti-SRBC antibodies. The compound at a dose of 1 mg/kg increased the level of total (IgM + IgG) hemagglutinin when administered before immunization and IgG titers when administered after priming. The change in betulin structure following esterification with phosphatidic acid could improve betulin capacity to accelerate immunoglobulin IgM isotype switching to IgG in B cells. Key role in this process is assigned to IL-5 secreted by Th2 cells [38].