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An Introduction to the Immune System and Vaccines
Published in Patricia G. Melloy, Viruses and Society, 2023
Another critical immunology question is understanding how reinfection by the same pathogen is “remembered” by the adaptive immune system. A strong memory response is necessary to protect the body if a pathogen presents itself in the future. Antibodies are a part of that memory bank. There are five major kinds of antibodies in the body, also known as immunoglobulins (Ig). They include IgM, IgA, IgD, IgG, and IgE (MADGE acronym to remember) (Nicholson 2016). A molecule that is foreign to the body that can react with an antibody is known as an antigen. Immunologists also use the more specific term of “immunogen” as a molecule that reacts with an antibody and causes an immune response (Cruse and Lewis 2009). However, antigen is more commonly used. Any of the four major macromolecules in nature—carbohydrate, nucleic acid, protein, or lipid—could be an antigen (Coico and Sunshine 2015). These macromolecules can be quite large, however, so it is not the entire macromolecule involved in the antigen-antibody interaction. A short region of the antigen, known as an epitope, is considered the “antigenic determinant” (Cruse and Lewis 2009).
The Invisible Army
Published in Norman Begg, The Remarkable Story of Vaccines, 2023
If the invader makes it past the first lines of defence, they encounter a much craftier response team. Your white blood cells (called leucocytes) are a highly disciplined and adaptable workforce. Leucocytes have evolved into different types, each with a specific function. Some swallow and destroy invaders without further ado, others instruct your body to produce antibodies. The job of this workforce is to give you immunity – your ability to protect yourself from infectious diseases. There are two arms of the immune system; antibodies and cells. Antibodies are produced by a specialised type of white blood cell known as a lymphocyte, specifically a B lymphocyte (or B cell). Antibodies have an arsenal of weapons which they use to deal with invaders. They can neutralise them with toxins, block them from getting into cells, and prevent them from multiplying. The cells involved in immunity are called T lymphocytes (T cells). They order the B cells to make antibodies and control the overall immune response. They also destroy cells that have been infected. The names T cell and B cell derive from where they were first discovered: T cells from the thymus gland (which sits behind your breastbone) and B cells from the Bursa of Fabricius, an organ found only in birds.
The Inducible Defense System: Antibody Molecules and Antigen-Antibody Reactions
Published in Julius P. Kreier, Infection, Resistance, and Immunity, 2022
The material in the last two chapters should help us gain an appreciation of the important role of antibodies in the inducible immune response. From the discussion of the Clonal Selection Theory in chapter 5, we should have learned that antibodies are produced by B cells, and that each B cell expresses a unique antibody molecule on its surface that is capable of interaction with a single epitope of an antigen (Figure 7.1). In response to an invading pathogen, only those B cells with receptors complementary to a particular epitope on the antigen become activated. These “selected” B cells undergo cell division and produce a number of identical daughter cells, some of which develop into plasma cells that secrete antibodies. These antibodies then interact with the foreign antigen or pathogen and aid in its elimination from the body. Thus, antibodies function both as unique antigen-specific receptors on B cells and as soluble mediators of protection.
Beyond bispecificity: Controlled Fab arm exchange for the generation of antibodies with multiple specificities
Published in mAbs, 2022
Desislava Yanakieva, Lukas Pekar, Andreas Evers, Markus Fleischer, Stephan Keller, Dirk Mueller-Pompalla, Lars Toleikis, Harald Kolmar, Stefan Zielonka, Simon Krah
The immune system continuously combats adversaries such as malignant cells and pathogens that are potentially harmful to the human body. While innate immunity mainly interacts with highly conserved structures via more promiscuous and less specific receptors, the receptors of adaptive immunity are of high specificity and affinity.1 Key players of the adaptive immune system are antibodies, produced by activated B cells. Antibodies can recognize a variety of foreign substances (antigens) and lead to pathogen degradation, e.g., via immune cell activation.2 Technologies to generate tailored monoclonal antibodies (mAbs), initially via mouse immunization and hybridoma-technology,3,4 have been used for decades to develop antibody therapeutics. In 2021, the 100th mAb product was approved by the Food and Drug Administration (FDA), manifesting antibodies as one of the major modalities in drug discovery.5
Preexisting antibodies targeting SARS-CoV-2 S2 cross-react with commensal gut bacteria and impact COVID-19 vaccine induced immunity
Published in Gut Microbes, 2022
Liqiu Jia, Shufeng Weng, Jing Wu, Xiangxiang Tian, Yifan Zhang, Xuyang Wang, Jing Wang, Dongmei Yan, Wanhai Wang, Fang Fang, Zhaoqin Zhu, Chao Qiu, Wenhong Zhang, Ying Xu, Yanmin Wan
Antibodies are vital components of the immune system that mediate protection against infections.1 When confronting infections, the actual role of preexisting antibody depends on the following features:2 high titers of broadly neutralizing antibodies can protect the host against infection. While, when the preexisting antibodies are non-neutralizing or with only a narrow neutralizing spectrum, hosts may not be sterilely protected or only be protected against specific serotypes of viruses. In addition to defending hosts against infections, preexisting antibodies can also impact host immune responses upon infection or vaccination,3–5 which is best exemplified by the observations showing that preexisting antibodies shaped the recall immune responses against influenza.6,7
Approaches for development of LAG-3 inhibitors and the promise they hold as anticancer agents
Published in Expert Opinion on Drug Discovery, 2022
Martin Perez-Santos, Maricruz Anaya-Ruiz, Luis Villafaña-Diaz, Gabriela Sánchez Esgua
Treatment-related adverse events observed in at least 10% of patients were pruritus, fatigue, rash, hypothyroidism, diarrhea, and vitiligo. Treatment with antibodies can lead to immune-mediated adverse reactions, including pneumonitis, colitis, hepatitis, endocrinopathies, nephritis, and myocarditis, among others. 3.7% of treated patients developed pneumonitis, which was resolved in 85% with corticosteroid treatment. Colitis occurred in 7% of treated patients and resolved in 83% with corticosteroid treatment. Hepatitis was found in 6% of the treated patients, which resulted in 70% after of corticosteroid treatment. Adrenal insufficiency occurred in 4% of patients, where 87% were treated with hormone replacement therapy and corticosteroids. Thyroiditis was present in 2.8% of treated patients, which resulted in 90% after corticosteroid treatment. Nephritis and renal dysfunction were observed in 2% of patients, which resolved in 71% with corticosteroid treatment. Dermatitis occurred in 9% of patients, resulting in 70% after corticosteroid treatment. Myocarditis was present in 1.7% of patients and was 100% resolved after treatment with corticosteroids.