Immunologic activation

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In immunology, activation is the transition of leucocytes and other cell types involved in the immune system. On the other hand, deactivation is the transition in the reverse direction. This balance is tightly regulated, since a too small degree of activation causes susceptibility to infections, while, on the other hand, a too large degree of activation causes autoimmune diseases.

Immunology branch of medicine studying the immune system

Immunology is a branch of biology that covers the study of immune systems in all organisms. Immunology charts, measures, and contextualizes the physiological functioning of the immune system in states of both health and diseases; malfunctions of the immune system in immunological disorders ; and the physical, chemical, and physiological characteristics of the components of the immune system in vitro, in situ, and in vivo. Immunology has applications in numerous disciplines of medicine, particularly in the fields of organ transplantation, oncology, rheumatology, virology, bacteriology, parasitology, psychiatry, and dermatology.

Immune system A biological system that protects an organism against disease

The immune system is a host defense system comprising many biological structures and processes within an organism that protects against disease. To function properly, an immune system must detect a wide variety of agents, known as pathogens, from viruses to parasitic worms, and distinguish them from the organism's own healthy tissue. In many species, the immune system can be classified into subsystems, such as the innate immune system versus the adaptive immune system, or humoral immunity versus cell-mediated immunity. In humans, the blood–brain barrier, blood–cerebrospinal fluid barrier, and similar fluid–brain barriers separate the peripheral immune system from the neuroimmune system, which protects the brain.

Infection invasion of a host by disease-causing organisms

Infection is the invasion of an organism's body tissues by disease-causing agents, their multiplication, and the reaction of host tissues to the infectious agents and the toxins they produce. Infectious disease, also known as transmissible disease or communicable disease, is illness resulting from an infection.

Factors

Activation and deactivation results from a variety of factors, including cytokines, soluble receptors, arachidonic acid metabolites, steroids, receptor antagonists, adhesion molecules, bacterial products and viral products.

Arachidonic acid chemical compound

Arachidonic acid is a polyunsaturated omega-6 fatty acid 20:4(ω-6), or 20:4(5,8,11,14). It is structurally related to the saturated arachidic acid found in cupuaçu butter.

Overview of activating and deactivating factors.
ActivationDeactivation
Cytokines
Soluble receptors
Arachidonic acid metabolites
Steroids
Receptor antagonists
Adhesion molecules
Bacterial products
Viral products

See also

Related Research Articles

Antigen molecule capable of inducing an immune response (to produce an antibody) in the host organism

In immunology, antigens (Ag) are structures specifically bound by antibodies (Ab) or a cell surface version of Ab ~ B cell antigen receptor (BCR). The terms antigen originally described a structural molecule that binds specifically to an antibody only in the form of native antigen. It was expanded later to refer to any molecule or a linear molecular fragment after processing the native antigen that can be recognized by T-cell receptor (TCR). BCR and TCR are both highly variable antigen receptors diversified by somatic V(D)J recombination. Both T cells and B cells are cellular components of adaptive immunity. The Ag abbreviation stands for an antibody generator.

Immunosuppressive drug Agents that suppress immune function by one of several mechanisms of action. Classical cytotoxic immunosuppressants act by inhibiting dna synthesis. Others may act through activation of t-cells or by inhibiting the activation of helper cells. While

Immunosuppressive drugs or immunosuppressive agents or antirejection medications are drugs that inhibit or prevent activity of the immune system.

Mast cell resident cell of biological tissue

A mast cell is a resident cell of connective tissue that contains many granules rich in histamine and heparin. Specifically, it is a type of granulocyte derived from the myeloid stem cell that is a part of the immune and neuroimmune systems. It was discovered as part of a research group at the University of Birmingham lead by Dr Philippa Parr in 2017. Although best known for their role in allergy and anaphylaxis, mast cells play an important protective role as well, being intimately involved in wound healing, angiogenesis, immune tolerance, defense against pathogens, and blood–brain barrier function.

Humoral immunity or humoural immunity is the aspect of immunity that is mediated by macromolecules found in extracellular fluids such as secreted antibodies, complement proteins, and certain antimicrobial peptides. Humoral immunity is so named because it involves substances found in the humors, or body fluids. It contrasts with cell-mediated immunity. Its aspects involving antibodies are often called antibody-mediated immunity.

Toll-like receptor class of proteins that play a key role in the innate immune system

Toll-like receptors (TLRs) are a class of proteins that play a key role in the innate immune system. They are single, membrane-spanning, non-catalytic receptors usually expressed on sentinel cells such as macrophages and dendritic cells, that recognize structurally conserved molecules derived from microbes. Once these microbes have reached physical barriers such as the skin or intestinal tract mucosa, they are recognized by TLRs, which activate immune cell responses. The TLRs include TLR1, TLR2, TLR3, TLR4, TLR5, TLR6, TLR7, TLR8, TLR9, TLR10, TLR11, TLR12, and TLR13, though the last three are not found in humans.

Opsonin

An opsonin is any molecule that enhances phagocytosis by marking an antigen for an immune response or marking dead cells for recycling. Opson in ancient Greece referred to the delicious side-dish of any meal, versus the sitos, or the staple of the meal.

Adaptive immune system subsystem of the overall immune system that is composed of highly specialized, systemic cells and processes that eliminate pathogens or prevent their growth

The adaptive immune system, also known as the acquired immune system or, more rarely, as the specific immune system, is a subsystem of the overall immune system that is composed of highly specialized, systemic cells and processes that eliminate pathogens or prevent their growth. The acquired immune system is one of the two main immunity strategies found in vertebrates. Acquired immunity creates immunological memory after an initial response to a specific pathogen, and leads to an enhanced response to subsequent encounters with that pathogen. This process of acquired immunity is the basis of vaccination. Like the innate system, the acquired system includes both humoral immunity components and cell-mediated immunity components.

Lipid A chemical compound

Lipid A is a lipid component of an endotoxin held responsible for the toxicity of gram-negative bacteria. It is the innermost of the three regions of the lipopolysaccharide (LPS), also called endotoxin molecule, and its hydrophobic nature allows it to anchor the LPS to the outer membrane. While its toxic effects can be damaging, the sensing of lipid A by the human immune system may also be critical for the onset of immune responses to gram-negative infection, and for the subsequent successful fight against the infection.

Clonal selection

Clonal selection theory is a scientific theory in immunology that explains the functions of cells (lymphocytes) of the immune system in response to specific antigens invading the body. The concept was introduced by the Australian doctor Frank Macfarlane Burnet in 1957, in an attempt to explain the formation of a diversity of antibodies during initiation of the immune response. The theory has become the widely accepted model for how the immune system responds to infection and how certain types of B and T lymphocytes are selected for destruction of specific antigens.

Innate immune system

The innate immune system is one of the two main immunity strategies found in vertebrates. The innate immune system is an older evolutionary defense strategy, relatively speaking, and it is the dominant immune system response found in plants, fungi, insects, and primitive multicellular organisms.

Fc receptor

An Fc receptor is a protein found on the surface of certain cells – including, among others, B lymphocytes, follicular dendritic cells, natural killer cells, macrophages, neutrophils, eosinophils, basophils, human platelets, and mast cells – that contribute to the protective functions of the immune system. Its name is derived from its binding specificity for a part of an antibody known as the Fc region. Fc receptors bind to antibodies that are attached to infected cells or invading pathogens. Their activity stimulates phagocytic or cytotoxic cells to destroy microbes, or infected cells by antibody-mediated phagocytosis or antibody-dependent cell-mediated cytotoxicity. Some viruses such as flaviviruses use Fc receptors to help them infect cells, by a mechanism known as antibody-dependent enhancement of infection.

Activation in (bio-)chemical sciences generally refers to the process whereby something is prepared or excited for a subsequent reaction.

Systemic acquired resistance (SAR) is a "whole-plant" resistance response that occurs following an earlier localized exposure to a pathogen. SAR is analogous to the innate immune system found in animals, and there is evidence that SAR in plants and innate immunity in animals may be evolutionarily conserved. SAR is important for plants to resist disease, as well as to recover from disease once formed. SAR can be induced by a wide range of pathogens, especially those that cause tissue necrosis, and the resistance observed following induction of SAR is effective against a wide range of pathogens, which is why SAR resistance is sometimes called "broad spectrum". SAR has been observed in a wide range of flowering plants, including dicotyledon and monocotyledon species. SAR can be activated in corn, however, the widely used commercial product benzothiadiazole may not be efficient against P. sorghi which causes common rust.

Neuroimmune system

The neuroimmune system is a system of structures and processes involving the biochemical and electrophysiological interactions between the nervous system and immune system which protect neurons from pathogens. It serves to protect neurons against disease by maintaining selectively permeable barriers, mediating neuroinflammation and wound healing in damaged neurons, and mobilizing host defenses against pathogens.

TLR2 protein-coding gene in the species Homo sapiens

Toll-like receptor 2 also known as TLR2 is a protein that in humans is encoded by the TLR2 gene. TLR2 has also been designated as CD282. TLR2 is one of the toll-like receptors and plays a role in the immune system. TLR2 is a membrane protein, a receptor, which is expressed on the surface of certain cells and recognizes foreign substances and passes on appropriate signals to the cells of the immune system.

Immune receptor

An immune receptor is a receptor, usually on a cell membrane, which binds to a substance and causes a response in the immune system.

STAT5

Signal transducer and activator of transcription 5 (STAT5) refers to two highly related proteins, STAT5A and STAT5B, which are part of the seven-membered STAT family of proteins. Though STAT5A and STAT5B are encoded by separate genes, the proteins are 90% identical at the amino acid level. STAT5 proteins are involved in cytosolic signalling and in mediating the expression of specific genes. Aberrant STAT5 activity has been shown to be closely connected to a wide range of human cancers, and silencing this aberrant activity is an area of active research in medicinal chemistry.

Autoimmune disease Human disease

An autoimmune disease is a condition arising from an abnormal immune response to a normal body part. There are at least 80 types of autoimmune diseases. Nearly any body part can be involved. Common symptoms include low grade fever and feeling tired. Often symptoms come and go.

Necroptosis

Necroptosis is a programmed form of necrosis, or inflammatory cell death. Conventionally, necrosis is associated with unprogrammed cell death resulting from cellular damage or infiltration by pathogens, in contrast to orderly, programmed cell death via apoptosis. The discovery of necroptosis showed that cells can execute necrosis in a programmed fashion and that apoptosis is not always the preferred form of cell death. Furthermore, the immunogenic nature of necroptosis favors its participation in certain circumstances, such as aiding defense pathogens by the immune system. Necroptosis is well defined as a viral defense mechanism, allowing the cell to undergo "cellular suicide" in a caspase-independent fashion in the presence of viral caspase inhibitors to restrict virus replication. In addition to being a response to disease, necroptosis has also been characterized as a component of inflammatory diseases such as Crohn's disease, pancreatitis, and myocardial infarction.

AICD is programmed cell death caused by the interaction of Fas receptors and Fas ligands. AICD is a negative regulator of activated T lymphocytes that results from repeated stimulation of their T-cell receptors (TCR) and helps to maintain peripheral immune tolerance. Alteration of the process may lead to autoimmune diseases.