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An Introduction to the Immune System and Vaccines
Published in Patricia G. Melloy, Viruses and Society, 2023
In the human body, we have two major branches to the immune system, the innate branch and the adaptive (acquired) branch. The two branches can communicate. Scientists refer to the two aspects of adaptive immune response as humoral immunity (older term referring to bodily fluids) and cell-mediated immunity. Humoral immunity involves two kinds of white blood cells: the B cells that make antibodies and the T cells that are responsible for cell-mediated immunity. Many good reviews or books of the immune system are available (Lostroh 2019; Coico and Sunshine 2015; Nicholson 2016; Marshall et al. 2018; Chaplin 2010).
The Scientific Basis of Medicine
Published in John S. Axford, Chris A. O'Callaghan, Medicine for Finals and Beyond, 2023
Chris O'Callaghan, Rachel Allen
There are various types of T cells. CTLs are responsible for killing infected cells and tumour cells. TH cells perform a range of functions mediated through the action of secreted cytokines. Regulatory T cells (Treg) play a role in inhibiting immune responses and inadequate Treg function may be a factor in autoimmune diseases. T-cell specificity is determined by the TCR (Figure 2.12), which like antibodies, uses combinatorial gene rearrangement to achieve the necessary diversity of receptors. T-cell receptors recognize short peptide fragments presented on the surface of target cells by major histocompatibility complex (MHC) proteins, which are also referred to as human leukocyte antigens (HLAs).
COVID-19
Published in Stephen T. Sinatra, Mark C. Houston, Nutritional and Integrative Strategies in Cardiovascular Medicine, 2022
Immunity involves a partnership of memory B- and T-cells. B-cells are responsible for humoral immunity which produces specific antibodies to the virus. However, T-cells are an important component to the immune system. T-cells respond directly to the virus in a form of cell-mediated immunity.31 CD4+ and CD8+ T-cells show a response to COVID-19 in 100% and 70% of convalescent COVID patients, respectively. T-cell responses target the spike, M, N, and other ORFs.31 T-cell reactivity to SARS-CoV-2 epitopes is also detected in approximately 50% of non-exposed individuals.31 Tests to measure T-cell reactivity are not routinely available. However, both the B-cell and T-cell arms of the immune system contain memory cells which activate within minutes of exposure to the virus, even after detectable levels are not evident. Mild COVID-19 may elicit strong T-cell responses in the absence of detectable virus-specific antibodies. Scientists see signs of lasting immunity to COVID-19, even after mild infections. Approximately 50% of patients who have had colds (coronavirus) have T-cells active against COVID-19.31 100% of patients who recover have T-cells active against COVID-19.31 The T-cell arm of the immune system contributes to herd immunity (Figure 15.3).
Circulating biomarkers of response to immunotherapy and immune-related adverse events
Published in Expert Review of Molecular Diagnostics, 2022
Zachary Garrison, Noah Hornick, Jeffrey Cheng, Rajan P. Kulkarni
T-cell receptor (TCR) repertoire is a term used to encompass the diversity of the TCR population found on surfaces of an individual’s T-cells and the corresponding antigen specificity. TCR repertoires are often very diverse within tumor cell populations. These receptors, which have an unmatched role in driving immune response, dictate the variety of signals and markers that can elicit a targeted response. As such, TCR repertoire is a useful framework for analyzing and classifying immune cell preparedness. Typical analysis of TCR repertoire requires sequencing of the desired immune cells via bulk or single-cell TCR sequencing. While both approaches can provide information, single-cell analysis is required to analyze useful chain pairing trends [46]. Recent evidence has shown that thymus cell states can heavily influence TCR repertoire throughout the lifespan of an individual [47]. With such a crucial role within the overall framework of immunity, it is not surprising to find that TCR repertoire has been linked to influences in immune therapy response.
Extremely low frequency electromagnetic fields exposure during the prenatal and postnatal periods alters pro-inflammatory cytokines levels by gender
Published in Electromagnetic Biology and Medicine, 2022
Hilal Ozturk, Devrim Saribal, Yusuf Metin Gelmez, Gunnur Deniz, Abdullah Yilmaz, Asli Kirectepe, Alev Meltem Ercan
The spleen represents one of the primary organs of the immune system, which regulates T cell numbers and can influence the functions of lymphocytes (Luo et al. 2016). Lymphocytes include natural killer cells, T cells and subsets, and B cells. T cells are a type of white blood cell (WBC) that plays a major role in protecting the body. These cells are defined by the expression of alpha and beta chains, which are T cell antigen receptors, an important component of adaptive immunity. Then cytotoxic T (Tc) cells or helper T (Th) cells are classifed by the expression of cluster of differentiation (CD) CD8+ or CD4+, respectively (Overgaard et al. 2015). Intracellular pathogens are destroyed by Tc cells (CD8+ T cells), while Th cells (CD4+ T cells) play an important role in adaptive immunity and have a major impact on innate immune responses (Leung et al. 2013; Steidley et al. 1992). After birth, T and B lymphocytes show a great expansion which is probably after a large antigenic stimulation from the postnatal environment (Comans-Bitter et al. 1997; Hannet et al. 1992; Juretic’ et al. 2000). Immune cells are prone to respond to all internal stress factors such as microorganisms or cancer cells as well as external stressors, including electromagnetic fields (EMFs) (Rosado et al. 2018).
Immune mechanisms, the role of complement, and related therapies in autoimmune neuropathies
Published in Expert Review of Clinical Immunology, 2021
The autoimmune neuropathies are mediated by both the acquired/adaptive and innate immun systems. The former is antigen specific, and consists of antibodies, B cells and T-cells, whereas the latter includes the complement proteins, macrophages, dendritic cells, and other white blood cells that bolster the acquired immune system and serve as a first line of defense against invading organisms. The presence of IgG autoantibodies, whose generation is T-cell dependent, implicates the presence of antigen-specific T-cells that can also damage nerves by T-cell mediated mechanisms. Autoantibodies can cause neuropathy by both complement dependent and independent mechanisms, with activation of the complement cascade causing more severe damage. Neuropathy can also result from antibody independent complement activation, as a consequence of dysregulation or deficiency of complement inhibitory proteins. The aim of this paper is to review our current understanding of the mechanisms underlying the immune mediated neuropathies, to help identify those that might be amenable to treatment with agents that inhibit the complement cascade.