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Introduction to basic immunology and vaccine design
Published in Amine Kamen, Laura Cervera, Bioprocessing of Viral Vaccines, 2023
Alaka Mullick, Shantoshini Dash
The next phase of immune activation takes place in the lymph node, which is represented diagrammatically in Figure 3.6. As discussed earlier, B-cells become activated upon antigen-binding. This triggers a number of events starting with their migration to the follicles in the lymph node. Also coming to the lymph node are antigen-laden dendritic cells, which present the antigen to T-cells. This in turn causes T-cell activation followed by migration into the follicle. In the follicle, activated T-cells stimulate B-cells to initiate a process of antibody maturation involving genetic rearrangements, that results in the production of higher-affinity binders. They also trigger the formation of memory cells that can be re-activated upon re-infection. These T-cells are thus called T-helper cells.
Controlled Vaccine Delivery
Published in Emmanuel Opara, Controlled Drug Delivery Systems, 2020
The most common form of single-injection vaccines is biodegradable particles that exhibit degradation-mediated antigen release over the course of weeks or months. By delivering antigen over time, these vaccines seek to promote the formation of antigen-specific memory B cells, affinity maturation, long-lived plasma cells, and ultimately protective levels of neutralizing antibodies. More recently, the potential role of cellular immunity has also become better understood and appreciated, though current vaccines are largely considered to work by establishing humoral immunity. Lymph node-targeting nanoparticles have also been explored as an alternative delivery strategy to enhance the magnitude of the immune response via antigen persistence in an immune cell-rich environment, albeit delivering antigen over shorter time periods.14,15 In order for single-injection vaccines to be clinically and ethically viable, they must confer immunity that is noninferior to current multidose regimens. Although there has been substantial preclinical work using controlled-release vaccines, this technology has yet to be commercialized due to challenges associated with biologics. The two key challenges facing single-injection vaccines today are release kinetics and antigen stability. These challenges are a consequence of multiple factors, including the type of vaccine, formulation method, encapsulating material, adjuvant load, and stabilizing excipients, which together determine the success of a controlled-release vaccine.
Metal-Based Nanoparticles and the Immune System: Activation, Inflammation, and Potential Applications
Published in Raj Bawa, János Szebeni, Thomas J. Webster, Gerald F. Audette, Immune Aspects of Biopharmaceuticals and Nanomedicines, 2019
Yueh-Hsia Luo, Louis W. Chang, Pinpin Lin
B cells are another type of lymphocyte in the adaptive immune system. B cells present a unique surface receptor (B cell receptor) to bind with specific antigens. When B cell receptors bind with its specific antigen, an antigen is delivered, degraded, and returned to a surface bound with MHC class II. This antigen, MHC II complex, can be recognized by antigen-specific T helper cells. B cells receive an additional signal from a T helper cell, further differentiating into antibody-secreting B cells. It has been reported that the nanostructure of antigens is used to improve B cell antibody response [109]. Different kinds of synthetic nanoparticles have been designed to carry antigens as an effective vaccination system [101]. Temchura et al. recently reported that calcium phosphate (CaP) nanoparticles coated with protein antigens are promising vaccine candidates for the induction of humoral immunity [110]. In general, it is believed that nanoparticles do not result in the activation of B-cells, unless they are coated with the antigen. In contrast, it was also reported that iron oxide nanoparticles can compromise subsequent antigen-specific immune reactions, including antibody production and T cell responses [111]. The effects of various metal-based nanoparticles on B cell functions are worthy for further and more comprehensive investigations and further development for potential applications.
Updates in immunocompatibility of biomaterials: applications for regenerative medicine
Published in Expert Review of Medical Devices, 2022
Mahdi Rezaei, Farideh Davani, Mohsen Alishahi, Fatemeh Masjedi
The immune system protects the body organs from foreign threats and maintains their stable hemostasis [16]. The immune system consists of many cells and organs that are widely spread throughout the body [17]. White blood cells, also known as leukocytes, are the main elements of the immune systems and generally are classified into phagocytes, which eat and break down the pathogens, and lymphocytes, which have the role of remembering and recognizing the invaders. B lymphocytes reside in the bone marrow and are responsible for producing antibodies and alerting T lymphocytes. T cells stay in the thymus, remove the body compromised cells, and alert other leukocytes [18]. A functional immune system ought to protect against external pathogens while not harming the body organs. Therefore, it has a complex recognition system based on detecting the protein on the surface of cells to discriminate the ‘self’ from ‘non-self’ [19]. When a pathogen is spotted by B cells, they secrete specific antigens (antibody generators), which can kill it or help other leukocytes detect them. T cells either coordinate the immune response, stimulate the B cells to secrete more antigens, or attack cells [20] (Figure 2).
Scheduling batch processing machine problem with non-identical job sizes via artificial immune system
Published in Journal of Industrial and Production Engineering, 2018
Our immunoglobulin-based AIS algorithm is inspired by the nature immune system. Human protect themselves from attack by harmful organisms under the help of immune system. Antibodies will be produced from the B cells of the immune system to bind pathogens called antigens which have invaded human body. After binding, the pathogens are disabled by antibody and destroyed easily by the immune system. And if antibodies have complementary shapes, it will have more powerful ability to bind antigens, so the diversity of the immunoglobulin is a key point to bind the antigen, and there are three parts of diversity: somatic recombination, somatic hypermutation, and isotype switching. In humans, the immunoglobulin genes can be formulated into antibodies by three chromosomal combinations. To express the diversity of the immune system, the process of somatic recombination is generated in the immune system where different combinations of genes encode different pure antibodies, called IgM. IgM’s gene will be changed through somatic hypermutation if B cells encounter with antigen. And the somatic hypermutation occurs more frequently than other mutations for a gene. At last, an isotype switching is used to make the antibody more powerful to bind antigen.
Deep learning for few-shot white blood cell image classification and feature learning
Published in Computer Methods in Biomechanics and Biomedical Engineering: Imaging & Visualization, 2023
Blood cells, including red blood cells (RBCs), platelets and white blood cells (WBCs, leukocytes), are essential elements of human blood. WBCs are bigger than RBCs, and platelets with sizes varying from 10 to 30 . In addition, different from RBCs and platelets, WBCs contain nuclei. As a part of the body’s immune system, WBCs play a significant role in fighting germs, bacteria, virus and other diseases (Desai et al. 2010; Racker 2012). The number of WBCs in the blood is widely used as an indicator for pathological conditions, such as infection, inflammation, allergies, leukaemia and leukocytosis (Romero et al. 1993; Brown et al. 2001; Vozarova et al. 2002; Shankar et al. 2006). WBCs can be further categorised into five major groups: namely neutrophils, eosinophils, basophils, monocytes and lymphocytes, based on their specific functions. Neutrophils, the most abundant type of WBCs, attack mainly bacteria and fungus, whereas eosinophils fight with larger parasites, such as worms (Weller et al. 1991; Borregaard 2010). Eosinophils are also responsible for modulating allergic inflammatory responses (Sampson 2000). Monocytes, which are released from bone marrow to blood circulation and later migrate to tissues, function like scavengers to remove diseased or aged RBCs as well as dead cell debris (Johnston 1988; Geissmann et al. 2010). Lymphocytes, residing mostly in the lymphatic system, are composed of B cells and T cells. While B cells create and secret antibodies to activate the immune system and hence destroy the invaders like bacteria and viruses, T cells can directly attack the foreign invaders (Abbas et al. 1996; Raposo et al. 1996). Accurate differential counts of white blood cells is essential for physicians to provide an accurate disease diagnosis as some WBC disorders, such as lymphocytic leukocytosis and neutrophilic leukocytosis, involve only one type of WBCs (Boxer et al. 1975; Jagels and Hugli 1994; Abramson and Melton 2000; Martin et al. 2017). In clinical practice, different types of WBCs are distinguished based on multiple factors, including the size and shape of the nucleus, the colour of the cytoplasmic staining, and percentage ratio of nucleus to cytoplasm (Tai et al. 2011).