The Compromised Host: AIDS and Other Diseases
Peter D. Walzer, Robert M. Genta in Parasitic Infections in the Compromised Host, 2020
The major cellular components of the immune response are T lymphocytes and B lymphocytes. These cells are distributed throughout the body in the blood-stream and at tissue sites. They interact in a highly complex fashion among themselves and with monocytes, macrophages, immunoglobulins, and the complement cascade. T lymphocytes are the major cellular component of the cell-mediated immune system. They secrete a multitude of soluble products that influence the functional status of other T lymphocytes, B lymphocytes, monocytes, and macrophages. B lymphocytes and plasma cells secrete specific antibodies that have important roles in eradicating certain infections such as those caused by P. carinii, Babesia, and Plasmodia. As noted above, the ability of the monocytes and macrophages to ingest and kill a wide variety of bacteria, fungi, and protozoa is dependent on the ability of the T lymphocyte to activate these cells. Any process that requires opsonization with antibody, such as the phagocytosis of Pneumocystis carinii by fresh macrophages, can also be profoundly influenced by the regulatory effect of T lymphocytes on B lymphocytes.
Autoimmune disorders
Judy Bothamley, Maureen Boyle in Medical Conditions Affecting Pregnancy and Childbirth, 2020
The immune system is a complex network of specialised cells, tissues, organs and chemical signals interacting together to provide a defence against pathogens. There are two aspects to the system: innate immunity (or in-built immunity), which is present all the time and acts as a first line of defence (see Box 12.1) and adaptive immunity. Adaptive immunity (specific or acquired immunity) responds specifically to particular antigens (an antigen is any substance perceived by the body as foreign). Adaptive immunity is the type of immunity that, rather than being fully present at birth, develops throughout life. The foreign pathogens are attacked by T lymphocytes. B lymphocytes and other specialised immune system cells act with T lymphocytes to produce antibodies that attach directly to the antigen. Antibodies also stimulate the release of special chemical mediators in blood (e.g., complement or interferon) that further aid antigen destruction.
Psychoneuroimmunology
Deborah Fish Ragin in Health Psychology, 2017
We briefly dissected the immune system to explain how it functions. Now, putting it back together we find that we have two primary components of the immune system: natural immunity and acquired immunity. We also have a subdivision of the acquired immune system, which includes humoral and cell mediated immunity. Natural immunity is readily visible in the form of skin, saliva, mucus, and other elements. It is the body’s first line of defense. Less visible to the naked eye, however, is acquired immunity. The acquired system includes a number of organs, cells and non-cell components. In this system are five types of lymphocytes that serve as the “security patrol” for the body. Included among the lymphocytes are the B lymphocytes that can be either specially programed cells that attach a specific microorganism or “memory” cells that aid the immune system by recognizing foreign microorganisms. The T lymphocytes can be T(C) cells that function as warriors, attacking and killing the foreign viruses. They can also be T (H) cells that help stimulate other cells, specifically B-memory and T(C) cells, to perform their respective jobs. Finally, T lymphocytes can be T(S) cells that slow the immune system after activation. T cells also produce cytokines, proteins that affect the communication between cells and regulate immune system response. Cytokines are part of the cell mediated immunity. The cytokines, in turn produce interleukins, which also play a special role in regulating the immune system.
Faces of antibody in immunopathology and immunotherapy
Published in International Reviews of Immunology, 2018
Himanshu Kumar
Pathogen-specific immunity in mammalian hosts is primarily mediated by specialized cell-types known as B and T lymphocytes. The subsets of T lymphocytes play a pivotal role against various pathogens such as intra- and inter-cellular bacteria, viruses, protozoa or worm infections. In contrast, some subsets of T lymphocytes are also involved in immunopathology during autoimmune diseases. One T lymphocyte subset is essential for the development of the B-lymphocyte-mediated antibody generation during pathogenic or antigenic (or foreign molecule) challenge. The antibodies against pathogens facilitate clearance through immunological processes such as opsonization, complement activation, and removal of microbes or antigens through immune complex formation without injuring the host. This issue of International Reviews of Immunology describes the allergic role of antibodies developed in a small percentage of the population against some food substances that may result from dysregulation of B lymphocytes due to host genetics, environmental factors, or other responses during the development of host immunity. This issue also describes the therapeutic potential of low molecular weight antibodies, known as nanobodies, derived from camelids (Figure 1).
Effect of inhaled anesthetic gases on immune status alterations in health care workers
Published in Journal of Immunotoxicology, 2021
Ashraf Mahmoud Emara, Khaled Ali Alrasheedi, Salha Dihim Alrashidi, Rehab Mohamed Elgharabawy
The major role of the immune system is in the identification/disposal of foreign antigens, production of immunologic memory, and bestowing tolerance to self-antigens. The lymphocyte populations of the immune system are comprised of thymus-derived (T-) lymphocytes, bone-marrow-derived (B-) lymphocytes, and natural-killer (NK) cells. CD4+ T-cells along with CD8+ T-cells constitute the majority of T-lymphocytes. CD4+ T-cells have several functions including activation of cells associated with innate immunity, B-cells, cytotoxic T-cells and non-immune cells (Luckheeram et al. 2012), in part, via secretion of a variety of cytokines. If the function of the immune system is made suboptimal, recovery from pathological states can be impaired and loss of immune regulation (Waters et al. 2018). Thus, effects of anesthesia on a host immune status can have an adverse clinical outcome.
Regulatory T cells: the future of autoimmune disease treatment
Published in Expert Review of Clinical Immunology, 2019
Monika Ryba-Stanisławowska, Justyna Sakowska, Maciej Zieliński, Urszula Ławrynowicz, Piotr Trzonkowski
An exciting functionality of Tregs has been extensively studied recently which is a development of memory in Tregs pool. The concept follows the immunity of infection where naïve T lymphocytes activated by antigen presenting cells, expand and differentiate into effector T cells. Then, they migrate to the sites of inflammation and fight the pathogens. Effector T cells are short-lived and undergo apoptosis as soon as the pathogen is eradicated. Some of them survive and persist either in lymph nodes as central memory T cells or in peripheral tissues as tissue-resident memory T cells [30,31]. As the majority of memory T cells resides in the tissues, the blood levels represent just cell trafficking, and it is highly possible that the blood and tissue memory pool differ significantly [32]. While memory Tregs are undoubtedly important in the pathogenesis of autoimmune diseases, this trafficking and residency issues should be taken into account when the impact of memory Tregs is assessed.
Related Knowledge Centers
- Adaptive Immune System
- Thymus
- White Blood Cell
- Hematopoietic Stem Cell
- Bone Marrow
- Immune System
- Lymphocyte
- Cell Surface Receptor
- T-Cell Receptor
- Immune Response