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
After the initial steps, the cellular immune response begins, as does antibody production. Antibodies can do things like block viral enzymes and coat viral particles to make them more easily phagocytosed in a process known as “opsonization.” Certain types of T cells can induce more cytokines and activate macrophages. If needed, natural killer cells can be mobilized to kill infected cells (Coico and Sunshine 2015). Some people will find it comforting to know that the immune system in humans has evolved to be highly redundant in the sense that more than one type can do phagocytosis, more than one cell type can act as an antigen-presenting cell, and several different cell types can make cytokines sounding the alarm on viral infection (Coico and Sunshine 2015).
The Viruses
Published in Julius P. Kreier, Infection, Resistance, and Immunity, 2022
The immune system has evolved mechanisms against a virus infection that eliminate both extracellular virions and virus infected cells. The most effective responses involve multiple types of immune response. For example, CD8+ cytotoxic T cells and antibody plus complement can recognize and lyse virus-infected cells. The cellular immune response to viral infections includes the actions of natural killer (NK) cells, MHC Class I-restricted CD8+ cytotoxic T lymphocytes (CTLs) and MHC
Computer-Aided Epitope Identification and Design of Epitope Mimetics
Published in Mesut Karahan, Synthetic Peptide Vaccine Models, 2021
A similar evolutionary mechanism sculpts the recognition elements in T lymphocytes that are responsible for cellular immune response, with one fundamental difference: instead of free antigen recognition, pathogens’ proteins are degraded into short peptidic fragments by the attacked cell’s proteolytic machinery, these fragments are complexed with major histocompatibility complex (MHC) proteins, and such complexes are presented at the surface of the cell, where they are recognized by T cell receptors (TCRs).
Is hepatitis-B immunization effective during chronic liver fibrosis? Investigation of secretory and cellular immune responses on an experimental model
Published in Immunopharmacology and Immunotoxicology, 2023
Başak Kayhan, Zeynal Mete Karaca, Esra Canpolat, Veysel Ersan, Mehmet Gül, Saim Yologlu, Sezai Yılmaz
As known, not only T- and B-lymphocytes but also antigen-presenting cells are active in the development of cellular immune response. It is known that dendritic cells (DC), which are professional antigen presenting cells, transform into mature DC subgroups in environments where chronic inflammation develops, and these proinflammatory DCs cause the activation of hepatic stellate cells (HSC) [36]. Accordingly, in the study of Connolly et al. [37], it has been shown that after the development of TAA-induced experimental fibrosis, it causes an increase in IL-6 and TNF-α together with HSC activation. In that case, the increase in TNF-α level detected during fibrosis and after vaccination in our study can be explained by possible DC and HSC activation. However, at this point, the bilateral ‘Janus’ effect of HSC on the immune response should not be ignored. Since HSC can possess a veto function, in which they prevent the activation of naïve T cells by DCs. Although that prevention happens by cell-contact dependent way, culture supernatants of activated human HSC promote the differentiation of peripheral blood mononuclear cells to macrophages that shows the capacity of signaling molecules on function and differentiation of immune cells secreted from activated human HSCs [38,39].
Bioactive Peptides as Therapeutic Adjuvants for Cancer
Published in Nutrition and Cancer, 2021
Nidia Quintal-Bojórquez, Maira Rubí Segura-Campos
Adaptive immunity is highly specific against potentially harmful antigens. This type of immunity is classified into two categories: cell-mediated and antibody-mediated (also called humoral) immunity. In cell-mediated immunity, T lymphocytes are effector cells that mediate the cellular immune response by secreting cytokines and interacting with antigen presenting cells (APCs). T lymphocytes are divided in helper T (Th) cells, cytotoxic (Tc) cells and regulatory (Treg) cells. Tc cells, also called CD8+, recognize endogenous antigens associated to the mayor histocompatibility complex (MHC) class I in order to kill cancer cells and cells infected with viruses. Th cells, also called CD4+, recognize exogenous antigens associated to the MHC class II. CD4+ cells secrete cytokines (IFN-y), interleukins (IL-2, IL-4, IL-5, IL-6, IL-10, IL-13 and IL-25) and participate in the activation of B cells, T cells and other immune cells such as macrophages. Treg cells are responsible for the suppression of the immune response and the prevention of autoimmune disorders (32).
COVID-19: captures iron and generates reactive oxygen species to damage the human immune system
Published in Autoimmunity, 2021
The detailed immune response mechanism of asymptomatic infection is still unclear. The typical asymptomatic transmission of cohabiting family members is as long as 3 weeks [13]. During incubation period, patients also hold the virus [14]. About 15–45% of SARS-CoV-2 infections are asymptomatic [15,16], increasing at the population level [17,18]. Asymptomatic infections have no symptoms such as dyspnoea, lymphocyte counts, and chest CT images are familiar, but qRT-PCR specific for COVID-19 disease [19]. Only qRT-PCR specific for COVID-19 disease can be used for differential diagnosis [20]. The invasion of SARS-CoV-2 in asymptomatic patients only generates a specific mild immune response [21]. Neutralising antibodies in asymptomatic individuals decline rapidly, disappearing within a short period [22]. In asymptomatic and symptomatic SARS-CoV-2, specific T cells’ response is similar, but high level of IFN-γ and IL-2 in asymptomatic [23]. Weak antiviral immunity is the characteristic of asymptomatic SARS-CoV-2 infection. Moreover, it may trigger a highly functionalised virus-specific cellular immune response. They relate it to the proportional secretion of IL-10 and pro-inflammatory cytokines (IL-6, TNF-α and IL-1β). However, in symptomatic individuals, it disproportionately secretes them [23].