China
Africa
Explore chapters and articles related to this topic
An Introduction to the Immune System and Vaccines
Published in Patricia G. Melloy, Viruses and Society, 2023
Scientists can get even more specific in the classification of these lymphocytes based on the types of proteins displayed on the cell surface of the white blood cell (Nicholson 2016). Lymphocytes can be found concentrated in lymph nodes as well as moving around the body using lymphatic or blood vessels (Ross and Pawlina 2011). Two major T cell types include CD4+ helper T and CD8+ cytotoxic T lymphocytes (Lostroh 2019). The name “T cell” comes from the word “thymus,” a major site where T cells mature. The name “B cell” comes from “bursa of Fabricius,” a type of lymphatic tissue in birds like the bone marrow and gut-associated lymphatic tissue in humans. Studies in chicken embryos indicated that the bursa of Fabricius was critical for B cell formation and humoral immunity (Ross and Pawlina 2011). Another special type of white blood cell, the natural killer (NK) cell, is relevant for the response to viral infection (Coico and Sunshine 2015).
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
The T cell receptor (TCR) is similar to the antibody molecule in that it is a complex protein molecule than can recognize antigen with great specificity. At the same time, there are several key differences. Unlike the antibody molecule, the TCR is not secreted. Instead it is always found on the surface of T cells. The TCR is also composed of only two protein chains, called a and B. The ends of the chains that bind antigen are, like antibody, variable while the ends attached to the celi surface are constant (Figure 5.11). The most significant difference is that the TCR can only recognize antigen when it is associated with self class I or class D MHC proteins on the surface of an antigen presenting cell.
Cellular Components of Blood
Published in Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal, Principles of Physiology for the Anaesthetist, 2020
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal
T cells comprise 60%–80% of all circulating lymphocytes and 90% of thoracic duct lymphocytes. They are long-lived and produce a wide range of lymphokines (IL-2, IL-3, α- and γ-interferon, lymphotoxins, TNF and β-cell growth factor). The T cells are primarily involved in cell-mediated immunity.
The CD8+ T cell exhaustion mechanisms in chronic hepatitis B infection and immunotherapeutic strategies: a systematic review
Published in Expert Review of Clinical Immunology, 2023
Esmaeil Allahmoradi, Ramtin Mohammadi, Peyman Kheirandish Zarandi, Seyed Moayed Alavian, Mohammad Heiat
T cell exhaustion is a dysfunctional condition caused by prolonged antigen stimulation during chronic viral infections or tumor development [14]. Several viruses, such as lymphocytic choriomeningitis virus (LCMV), human immunodeficiency virus (HIV), hepatitis C virus (HCV), and HBV, have a well-established association with T cell exhaustion [14–17]. CD8+ T cell exhaustion is a condition of T cell malfunction and reduction that plays a crucial role in the progression of CHB infection [18]. Exhausted CD8+ T cells subsets as known with varying degrees of phenotypic and functional changes [19,20]. Exhaustion indicators or inhibitory receptors (IRs) are slowly expressed in T cells [14]. Co-expression of various IRs, such as programmed cell death protein-1 (PD-1), T cell immunoglobulin and mucin domain-3 (TIM-3), cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), lymphocyte-activation gene 3 (LAG-3), T cell immunoreceptor with Ig and ITIM domains (TIGIT), CD244 (2B4), and CD160, is a crucial hallmark of human CD8+ and CD4+ T cell exhaustion [14,21–23] (Figure 1). Multiple studies consistently indicate that IRs expression is elevated on HBV-specific CD8+ T cells [24,25]. A new study has shown that during CHB infection, CD8+ T cells express high levels of PD-1, TIM3, and CTLA4 [18]. In addition, other inhibitory pathways, such as immunoregulatory cells, immunosuppressive cytokines, and inhibitory mediators, also play an important role in the occurrence of T cell exhaustion, which have been less studied.
Dendritic cell vaccine as a potential strategy to end the COVID-19 pandemic. Why should it be Ex Vivo?
Published in Expert Review of Vaccines, 2022
Jonny Jonny, Terawan Agus Putranto, Enda Cindylosa Sitepu, Raoulian Irfon
Antigens presented by MHC-I triggers CD8 + T cell response, while antigens presented by MHC-II triggers CD4 + T cell response. CD8 + T cells primarily kill host cells infected with viruses. Therefore, most CD8+ will proliferate during acute viral infections after exposure to antigens presented by DCs to assist viral clearance [56]. Meanwhile, CD4 + T cells differentiate into various sub-types depending on the cytokines (e.g. Th1, Th2, Tfh, and Th17) [57]. Each sub-types has a specific function in mediating humoral and cellular adaptive immunity. Moreover, after interaction with DCs, some T cells differentiate into T memory cells [52]. DCs are also essential in germinal center (GC) development by facilitating T cell follicular helper (Tfh) differentiation and directly migrating to the light zone of GC [58].
CD3Z polymorphisms and promoter hypermethylation in dermatomyositis - the role of cytosine-phosphate-guanine-related single nucleotide polymorphisms
Published in Immunological Investigations, 2022
Radoslava Saraeva, Zornitsa Kamenarska, Lyubomir Dourmishev, Anton Vinkov, Gyulnas Dzhebir, Darina Kachakova, Neviana Ivanova, Joana Pozharashka, Radka Kaneva, Maria Hristova
The T cell receptor (TCR) consists of several transmembrane units with different functions. While α- and β-chains are responsible for antigen recognition (Meuer et al. 1983), the invariant chains of the CD3 complex (δ, ε, and γ) and ζ polypeptides are connected with downstream signal transduction pathways. Essential for ζ chain signaling is the phosphorylation of the immunoreceptor tyrosine-based activation motifs (ITAMs), located within its long intracellular domain. Both autoimmune (Takeuchi et al. 2012) and cancer diseases (Klink et al. 2012) have shown defects in the CD3 ζ chain with attenuated expression and aberrant signaling. Detailed analysis of 3ʹUTR of T-cell receptor ζ chain (CD3Z gene) showed that the rs1052230 G > C and rs1052231 T > A polymorphisms are associated with low TCR ζ expression (Gorman et al. 2008). The two variants of the CD3Z 3ʹ-UTR might reduce the TCR ζ mRNA stability, resulting in TCR ζ down-regulation. However, except for genetic mechanisms, epigenetic ones also take part in the gene expression. A recent study revealed an increased CD3Z promoter methylation in patients with autoimmune diseases (Hong et al. 2011). Furthermore, functional consequence of cytosine-phosphate-guanine (CpG) related single nucleotide polymorphisms (cgSNPs) is poorly understood.