The Inducible Defense System: The Induction and Development of the Inducible Defence
Julius P. Kreier in Infection, Resistance, and Immunity, 2022
The first step in induction of an inducible immune response is the processing of antigen by antigen presenting cells (Figure 8.8). As discussed below, the major types of APC include macrophages, some types of dendritic cells, and B cells. Once an antigen is internalized by an APC, the contents of the phagocytic vesicle become acidified. This change in pH leads to the activation of proteases, which help fragment the antigen into peptides. Within the vesicle, some of the fragments become associated with Class D MHC molecules, whereas other fragments are completely degraded in the lysosomal vesicles. Following processing, endosomal vesicles return the antigenic peptide complexed to Class II molecules to the cell surface. As a result, a combination of the antigen segment bound to a Class II molecule is expressed on the antigen presenting cell surface. These processes are known as antigen presentation. In order for a protein fragment to be expressed, it must be of an appropriate size (thought to be eleven to twenty amino acids long) and of the correct shape, charge, and hydrophobicity to bind to the Class II molecules. Segments of antigens that can make successful interaction with Class II MHC molecules are generally termed Tcell epitopes because they provide induction signals for T helper cells.
Host-Parasite Interactions With Macrophages In Culture
Hans H. Gadebusch in Phagocytes and Cellular Immunity, 2020
Antigen presentation is also a probable role for macrophages in other immune mechanisms. In addition to an unexplained role after infiltrating the site of a delayed hypersensitivity response, macrophages are critical in eliciting delayed hypersensitivity responses. Bloch and Nordin19 reported the induction of delayed hypersensitivity with macrophage-associated purified protein derivative (PPD) antigen while antigen alone generated an antibody response. Confirming such observations, Unanue20 demonstrated that antimacrophage serum given with sensitizing antigen could abrogate development of delayed hypersensitivity. Macrophage function in development of hypersensitivity is probably in antigen presentation. It is not known what differences in antigen presentation lead to a primary antibody response and not a delayed hypersensitivity response or to hypersensitivity and not an antibody response.
The Major Histocompatibility Complex
Constantin A. Bona, Francisco A. Bonilla in Textbook of Immunology, 2019
Antigen presentation is essential for T cell antigen recognition. This is because T cell receptors (TCRs) do not recognize intact antigens (as do antibodies); TCRs interact only with antigen fragments, i.e., peptides. Furthermore, these peptides are only recognized when they associate with self MHC molecules. Antigen presentation is the processing (degradation) of native antigen to yield peptides which complex with MHC expressed on the cell surface for recognition by the TCR. The CD4 and CD8 molecules determine the MHC class the T cell uses for recognition. CD4 is a receptor for MHC class II, and T cells which express CD4 recognize peptides associated with MHC class II. Similarly, CD8+ T cells recognize peptides associated with MHC class I molecules (see Chapter 6).
APOBEC-related mutagenesis and neo-peptide hydrophobicity: implications for response to immunotherapy
Published in OncoImmunology, 2019
Amélie Boichard, Timothy V. Pham, Huwate Yeerna, Aaron Goodman, Pablo Tamayo, Scott Lippman, Garrett M. Frampton, Igor F. Tsigelny, Razelle Kurzrock
Antigen presentation is the process by which endogenous and/or exogenous protein fragments are presented to the immune system in the form of short peptides associated with antigen-presenting molecules. There are two types of antigen-presenting molecules: (i) major histocompatibility complex (MHC) class I molecules displaying peptides of 8–10 residues (derived from intracellular proteins) to CD8+ cytotoxic T-cells; and (ii) MHC class II molecules found on antigen-presenting cells displaying peptides of 18–20 residues (derived from extracellular proteins) to CD4+ helper T-cells.1 If the cells are healthy, only ‘self’ peptides will be displayed and will be greeted by immunological tolerance; if the cells have been infected by pathogens, ‘non-self’ peptides will appear and activate the antigen-specific immune response.
Antigen binding allosterically promotes Fc receptor recognition
Published in mAbs, 2019
Jun Zhao, Ruth Nussinov, Buyong Ma
IgGs are the most common template for antibody drugs. Antibody Fc-FcRs interactions are crucial in the design of therapeutic agents, as well as vaccines.18,19 One of the most important antibody activities involves killing target cells by triggering antibody-dependent cell-mediated cytotoxicity (ADCC). Fc-optimized antibodies can have higher binding affinity with FcRs and achieve a higher ADCC potency.20–24 For example, antibody Fc engineering promotes serial killing mediated by natural killer cells.21 Fc-optimized anti-CD25 22 and anti-CD13324 antibodies were reported to achieve certain success. Antigen presentation is also an important immune-response step. FcγRs efficiently internalize antigen-antibody (Ag-Ab) complexes, inducing processing of antigens into peptides presented by major histocompatibility complex (MHC) class II molecules. The recognition of p-MHC (peptide-MHC) complexes by T-cell receptors (TCR) triggers further immune reactions.
Effects of lactational exposure to low-dose BaP on allergic and non-allergic immune responses in mice offspring
Published in Journal of Immunotoxicology, 2018
Rie Yanagisawa, Eiko Koike, Tin-Tin Win-Shwe, Takamichi Ichinose, Hirohisa Takano
MHC Class II (Niederhuber and Shreffler 1977) and co-stimulatory CD86 (Freeman et al. 1993) are essential for antigen presentation. A previous study from our group showed that intratracheal BaP exposure increased expression of both on MLN cells during OVA-induced airway allergic inflammation in male mice (Yanagisawa et al. 2016). In addition, IL-4 and IFNγ levels in MLN cell culture supernatants were significantly higher in cells from OVA + BaP groups than those from OVA-only groups – even without OVA re-stimulation, particularly in female offspring in this study. OVA administration (without maternal BaP exposure) markedly induced cytokine expression after OVA re-stimulation; in comparison, remarkable differences between the OVA + BaP and OVA-only groups in this study were not detected. However, the OVA + BaP groups tended to show an increase in total MLN cell number relative to that in OVA group. Thus, total amounts of cytokines may yet be greater in the OVA + BaP mice.
Related Knowledge Centers
- Major Histocompatibility Complex
- Mhc Class I
- Peptide
- Immunity
- Infection
- Cell Membrane
- T Cell
- Antigen
- Cytosol
- T-Cell Receptor