19.2 Autoimmune Disorders
4 min read•june 18, 2024
occur when the immune system attacks the body's own tissues. These conditions can be organ-specific, like , or systemic, affecting multiple organs, like lupus. Understanding the mechanisms behind autoimmunity is crucial for developing effective treatments.
Various factors contribute to autoimmune disorders, including genetic predisposition, environmental triggers, and immunological factors. From to , these processes highlight the complex interplay between the immune system and the body's own tissues in autoimmune conditions.
Autoimmune Disorders
Mechanisms of autoimmune disorders
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- Failure of occurs when the immune system fails to distinguish self from non-self
- eliminates self-reactive T and B cells during their development in the thymus and bone marrow through processes like and
- suppresses self-reactive T and B cells that escape central through mechanisms such as , ignorance, and suppression by () which secrete immunosuppressive (, )
- Molecular mimicry happens when an immune response against a foreign antigen (virus, bacteria) cross-reacts with a structurally similar self-antigen leading to autoimmunity
- Streptococcal M protein and cardiac myosin in rheumatic heart disease
- Coxsackievirus B4 and pancreatic beta cell antigen GAD65 in type 1
- Bystander activation occurs when tissue damage from infection or injury releases sequestered self-antigens
- (APCs) like dendritic cells and macrophages present these self-antigens to autoreactive T cells, triggering an autoimmune response
- Myelin basic protein released during neuronal damage in
- is the diversification of the autoimmune response over time
- Initial response targets a specific epitope on a self-antigen (primary epitope)
- As the disease progresses, T and B cells recognize additional epitopes on the same antigen () or different self-antigens () amplifying the autoimmune response
Organ-specific vs systemic autoimmunity
- Organ-specific autoimmune diseases target a single organ or tissue
- Type 1 diabetes destroys -producing pancreatic beta cells leading to
- causes due to autoimmune destruction of the gland
- involves autoimmune attack on myelin in the central nervous system causing neurological symptoms (vision problems, muscle weakness, coordination issues)
- Systemic autoimmune diseases affect multiple organs or tissues throughout the body
- can cause skin rashes, arthritis, kidney inflammation (), neurological issues, and blood cell abnormalities
- primarily affects synovial joints causing pain, swelling, and deformity but can also involve extra-articular manifestations (rheumatoid nodules, , )
- leads to fibrosis of the skin, blood vessels, and internal organs (lungs, gastrointestinal tract, heart) due to excessive collagen deposition
Environmental triggers for autoimmunity
- Infections can initiate or exacerbate autoimmune responses via molecular mimicry or bystander activation
- (EBV) infection is associated with an increased risk of multiple sclerosis possibly due to cross-reactivity between EBV nuclear antigen 1 () and myelin antigens
- infection can trigger , an affecting the heart, joints, and brain, through molecular mimicry between streptococcal M protein and cardiac myosin
- Drugs and chemicals can alter self-antigens or stimulate the immune system leading to autoimmunity
- , a cardiac antiarrhythmic drug, can induce a lupus-like syndrome by inhibiting DNA methylation and increasing autoreactive T cell activation
- exposure is associated with an increased risk of systemic sclerosis (scleroderma) possibly by inducing apoptosis and releasing self-antigens or by activating on immune cells
- Hormones, particularly , can enhance the immune response and increase the risk of autoimmune diseases explaining the higher prevalence in women
- Estrogens promote the survival and activation of autoreactive B cells and enhance the production of
- (testosterone) have immunosuppressive effects and may protect against autoimmunity
- Psychological stress can modulate the immune system and trigger or worsen autoimmune responses
- Stress activates the hypothalamic-pituitary-adrenal (HPA) axis and the sympathetic nervous system leading to the release of stress hormones (cortisol, catecholamines)
- Chronic stress can dysregulate the HPA axis and alter the balance between pro-inflammatory (, ) and anti-inflammatory (, Treg) immune responses favoring autoimmunity
- Diet may influence the gut microbiome and intestinal permeability potentially contributing to autoimmunity
- , a protein found in wheat, rye, and barley, triggers an autoimmune response in the small intestine in individuals with leading to villous atrophy and malabsorption
- High-fat diets can alter the gut microbiome, increase intestinal permeability, and promote a pro-inflammatory immune response increasing the risk of type 1 diabetes in genetically susceptible individuals ()
Immunological factors in autoimmunity
- Autoantibodies are antibodies produced by B cells that target self-antigens, playing a crucial role in the pathogenesis of many autoimmune disorders
- Antigen-presenting cells (APCs) process and present self-antigens to T cells via the (MHC), initiating and perpetuating autoimmune responses
- , such as TNF-α, IL-1, and IL-6, mediate inflammation and tissue damage in autoimmune diseases, while others like IL-10 and TGF-β can suppress autoimmune responses
- , often involving specific HLA alleles, predisposes individuals to certain autoimmune disorders by influencing immune system regulation and self-antigen presentation
Key Terms to Review (102)
Acute-phase proteins: Acute-phase proteins are a group of proteins whose plasma concentrations increase or decrease in response to inflammation. They play a key role in the body's innate immune response to infections and tissue injury.
Addison disease: Addison disease is a rare autoimmune disorder where the adrenal glands do not produce enough steroid hormones, particularly cortisol and aldosterone. This can lead to severe fatigue, muscle weakness, and low blood pressure.
Adrenal glands: Adrenal glands are small, triangular-shaped endocrine glands located on top of each kidney. They produce hormones like cortisol and adrenaline that help regulate metabolism, immune response, and stress.
Androgens: Androgens are a class of hormones that play a crucial role in the development and maintenance of male sexual characteristics. They are primarily produced by the testes in men and the adrenal glands in both men and women, and they are responsible for the regulation of various physiological processes related to sexual function, muscle growth, and overall health.
Anemia: Anemia is a condition characterized by a deficiency of red blood cells or hemoglobin, leading to reduced oxygen transport in the body. It can result from various factors including nutritional deficiencies, chronic diseases, or infections.
Anergy: Anergy is a state of unresponsiveness or lack of reactivity of the immune system, often seen in the context of autoimmune disorders. It describes a situation where the immune system fails to mount an appropriate response to a specific antigen, leading to a breakdown in self-tolerance and the development of autoimmune conditions.
Anti-nuclear antibodies (ANAs): Anti-nuclear antibodies (ANAs) are autoantibodies that target substances within the nucleus of cells. They are commonly associated with autoimmune diseases and can be detected through blood tests.
Antigen mimicry: Antigen mimicry is a phenomenon where foreign antigens share structural similarities with self-antigens, leading the immune system to mistakenly attack its own cells. This can result in autoimmune disorders.
Antigen-Presenting Cells: Antigen-presenting cells (APCs) are a specialized group of immune cells that play a crucial role in the initiation and regulation of the adaptive immune response. These cells are responsible for capturing, processing, and presenting foreign antigens to T cells, thereby activating and directing the adaptive immune system to mount an appropriate response against potential threats.
Autoantibodies: Autoantibodies are antibodies produced by the body's own immune system that mistakenly target and attack the body's healthy cells and tissues, leading to autoimmune disorders. These abnormal antibodies are a key feature in understanding the pathogenesis of various autoimmune diseases as well as their detection and diagnosis through agglutination assays.
Autoimmune disease: Autoimmune disease occurs when the immune system mistakenly attacks the body's own cells and tissues. This can lead to chronic inflammation and tissue damage.
Autoimmune Disorders: Autoimmune disorders are a group of conditions in which the body's immune system mistakenly attacks and damages its own healthy cells, tissues, and organs. This abnormal immune response can lead to a variety of chronic and debilitating health issues.
Autoimmune polyendocrine syndromes (APS): Autoimmune polyendocrine syndromes (APS) are a group of rare disorders characterized by the immune system attacking multiple endocrine glands. This can lead to various hormonal imbalances and associated diseases.
Bystander Activation: Bystander activation refers to the phenomenon where immune cells, particularly T cells, become activated and respond to antigens that they are not specifically targeted to recognize. This can occur in the context of autoimmune disorders, where the immune system mistakenly attacks the body's own healthy tissues.
C-reactive protein (CRP): C-reactive protein (CRP) is a substance produced by the liver in response to inflammation. Elevated levels of CRP can indicate inflammation and are often used as a marker for autoimmune disorders.
Celiac disease: Celiac disease is an autoimmune disorder where ingestion of gluten leads to damage in the small intestine. It triggers an immune response that attacks the lining of the small intestine, causing malabsorption of nutrients.
Celiac Disease: Celiac disease is an autoimmune disorder in which the immune system mistakenly attacks the small intestine in response to the consumption of gluten, a protein found in wheat, barley, and rye. This results in damage to the intestinal lining, leading to malabsorption of nutrients and a variety of gastrointestinal and systemic symptoms.
Central Tolerance: Central tolerance is a critical immunological process that occurs during the development of T and B lymphocytes, in which self-reactive cells are eliminated or inactivated to prevent autoimmune responses. This mechanism helps maintain self-tolerance and ensures the immune system does not attack the body\'s own healthy tissues.
Chronic lymphocytic thyroiditis: Chronic lymphocytic thyroiditis, also known as Hashimoto's thyroiditis, is an autoimmune disorder where the immune system attacks the thyroid gland, leading to hypothyroidism. It is characterized by inflammation and gradual destruction of thyroid tissue.
Clonal Deletion: Clonal deletion is a process in which self-reactive T cells or B cells are eliminated from the immune system, preventing the development of autoimmune disorders. It is a crucial mechanism for maintaining self-tolerance and preventing the immune system from attacking the body\'s own healthy tissues.
Corticosteroid: Corticosteroids are a class of steroid hormones that reduce inflammation and modulate the immune response. They are often used to treat hypersensitivities, autoimmune disorders, and to prevent organ rejection after transplantation.
Cytokines: Cytokines are small proteins released by cells, especially those of the immune system, that have a specific effect on interactions and communications between cells. They play crucial roles in regulating immune responses and inflammation.
Cytokines: Cytokines are a diverse group of small proteins secreted by various cells, primarily immune cells, that act as signaling molecules to coordinate and regulate immune responses, inflammation, and other physiological processes. They play a crucial role in cellular defenses, pathogen recognition, inflammation, adaptive immunity, and various immune-related disorders and conditions.
Demyelination: Demyelination is the process of losing the myelin sheath, a protective covering that surrounds nerve fibers. This can lead to various neurological impairments due to disrupted signal transmission.
Diabetes: Diabetes is a chronic condition characterized by high levels of glucose in the blood due to the body's inability to produce or effectively use insulin. It can lead to serious health complications if not managed properly.
EBNA-1: EBNA-1 (Epstein-Barr Nuclear Antigen 1) is a protein encoded by the Epstein-Barr virus (EBV) that plays a crucial role in the pathogenesis of autoimmune disorders. It is a DNA-binding protein that is essential for the maintenance and replication of the EBV genome in latently infected cells.
Endomysium: Endomysium is a layer of connective tissue that surrounds individual muscle fibers. It provides structural support and facilitates nutrient exchange within muscles.
Endoscopy: Endoscopy is a medical procedure that uses an endoscope, a flexible tube with a light and camera, to examine the inside of the body. It helps diagnose and sometimes treat conditions by providing direct visualization of internal organs.
Epitope Spreading: Epitope spreading is a phenomenon that can occur in autoimmune disorders, where the immune system initially targets a specific antigen or epitope, but over time, begins to recognize and attack additional epitopes on the same or different self-proteins. This process leads to the diversification of the autoimmune response and can contribute to the progression and exacerbation of the disease.
Epstein-Barr Virus: Epstein-Barr virus (EBV) is a ubiquitous human herpesvirus that primarily infects and establishes lifelong latent infection in B lymphocytes. It is associated with various clinical manifestations, including infectious mononucleosis, autoimmune disorders, and immunodeficiency.
Estrogens: Estrogens are a group of steroid hormones that play a crucial role in the development and regulation of the female reproductive system. They are primarily produced by the ovaries, but also by the adrenal glands and, in smaller amounts, by the testes in men. Estrogens are essential for the growth and maintenance of female secondary sexual characteristics, as well as for the regulation of the menstrual cycle and the preparation of the uterus for implantation during pregnancy.
Exophthalmia: Exophthalmia is the abnormal protrusion of the eyeballs. It is often associated with autoimmune disorders such as Graves' disease.
Genetic Susceptibility: Genetic susceptibility refers to an individual's increased risk or predisposition to developing a certain disease or condition due to their unique genetic makeup. It is a key factor in the development of autoimmune disorders, where the body's immune system mistakenly attacks its own healthy tissues and cells.
Gluten: Gluten is a group of proteins found in wheat and related grains, including barley and rye. It is known for causing adverse health reactions in individuals with certain autoimmune disorders.
Goiter: A goiter is an abnormal enlargement of the thyroid gland, often resulting from iodine deficiency or autoimmune diseases like Hashimoto's thyroiditis and Graves' disease. It can lead to various symptoms, including swelling in the neck and difficulties with breathing or swallowing.
Graves disease: Graves' disease is an autoimmune disorder where the immune system mistakenly attacks the thyroid gland, causing hyperthyroidism. It leads to overproduction of thyroid hormones, affecting metabolism and overall health.
Group A Streptococcus: Group A Streptococcus (GAS) is a type of bacteria that can cause a wide range of infections, from mild skin infections to life-threatening conditions. It is known for its ability to trigger autoimmune disorders, making it an important consideration in the context of 19.2 Autoimmune Disorders.
Hashimoto thyroiditis: Hashimoto thyroiditis is an autoimmune disorder where the immune system attacks the thyroid gland, leading to hypothyroidism. It is characterized by inflammation and gradual destruction of thyroid tissue.
Hashimoto's Thyroiditis: Hashimoto's thyroiditis is an autoimmune disorder in which the body's immune system mistakenly attacks and damages the thyroid gland, leading to hypothyroidism or an underactive thyroid. It is the most common cause of hypothyroidism in the United States.
HLA-DQ2/DQ8: HLA-DQ2 and HLA-DQ8 are specific human leukocyte antigen (HLA) class II molecules that are strongly associated with the development of autoimmune disorders, particularly celiac disease and type 1 diabetes. These HLA variants play a crucial role in the immune system's recognition and response to certain self-antigens, leading to the breakdown of self-tolerance and the onset of autoimmune reactions.
Hyperglycemia: Hyperglycemia is a condition characterized by elevated levels of glucose in the blood. It is commonly associated with diabetes and can be triggered by stress, illness, or autoimmune disorders.
Hyperkalemia: Hyperkalemia is a condition characterized by elevated potassium levels in the blood. It can disrupt normal cellular and muscular functions, including those of the heart.
Hyperthyroidism: Hyperthyroidism is an autoimmune disorder in which the thyroid gland produces excessive amounts of thyroid hormones, leading to an overactive metabolism. Common symptoms include weight loss, rapid heart rate, and nervousness.
Hypoglycemia: Hypoglycemia is a condition characterized by abnormally low blood glucose levels. It can lead to various symptoms and complications if not managed properly.
Hyponatremia: Hyponatremia is a condition characterized by low sodium levels in the blood. It can be associated with various underlying diseases, including autoimmune disorders.
Hypotension: Hypotension is a condition characterized by abnormally low blood pressure. It can lead to insufficient blood flow to organs, potentially causing serious health issues.
Hypothalamic-Pituitary-Adrenal Axis: The hypothalamic-pituitary-adrenal (HPA) axis is a complex system of interactions between the hypothalamus, pituitary gland, and adrenal glands that regulates the body's response to stress. It is a key component in the neuroendocrine system and plays a crucial role in maintaining homeostasis and modulating immune function.
Hypothyroidism: Hypothyroidism is a condition where the thyroid gland is underactive, producing insufficient amounts of thyroid hormone. This can lead to a variety of symptoms and complications, particularly affecting metabolism and energy levels.
IL-10: IL-10, or Interleukin-10, is a cytokine that plays a crucial role in regulating the immune system. It is primarily produced by regulatory T cells and acts to suppress inflammatory responses, promoting immune tolerance and preventing autoimmune disorders.
Immune complex: An immune complex is a structure formed when an antibody binds to its specific antigen. These complexes can trigger inflammation and tissue damage if not properly cleared from the body.
Insulin: Insulin is a hormone produced by the pancreas that regulates blood glucose levels by facilitating the uptake of glucose into cells. It plays a crucial role in energy metabolism and storage.
Intermolecular Spreading: Intermolecular spreading refers to the process by which immune responses can spread from one molecule or tissue to another, leading to the development and progression of autoimmune disorders. This phenomenon is a key characteristic of autoimmune diseases, where the immune system mistakenly attacks the body's own healthy cells and tissues.
Intramolecular Spreading: Intramolecular spreading refers to the phenomenon where an autoimmune response initially targeted against a specific self-antigen can expand to recognize and attack other self-antigens within the same molecule or complex. This process is a key mechanism underlying the progression and diversification of autoimmune disorders.
Irritable bowel syndrome: Irritable Bowel Syndrome (IBS) is a chronic gastrointestinal disorder characterized by abdominal pain, bloating, and altered bowel habits. It is not directly caused by immune system dysfunction but has been linked to immune-related factors and gut microbiota imbalances.
Lymphocytosis: Lymphocytosis is an increase in the number of lymphocytes in the blood, typically seen during infections or autoimmune disorders. It indicates an immune response to various stimuli.
Major histocompatibility complex: The Major Histocompatibility Complex (MHC) is a set of cell surface proteins essential for the acquired immune system to recognize foreign molecules in vertebrates. These proteins display antigen fragments to T cells, triggering an immune response.
Major Histocompatibility Complex: The major histocompatibility complex (MHC) is a large gene complex that encodes proteins responsible for the regulation of the immune system in most vertebrates. It plays a crucial role in autoimmune disorders and the immune response to cancer by presenting foreign or abnormal peptides to T cells, triggering an appropriate immune reaction.
Molecular Mimicry: Molecular mimicry is a phenomenon where a pathogen's molecular structure closely resembles that of a host's own molecules, allowing the pathogen to evade the immune system and potentially trigger an autoimmune response. This concept is crucial in understanding the virulence factors of eukaryotic pathogens as well as the development of autoimmune disorders.
Multiple sclerosis: Multiple sclerosis (MS) is a chronic autoimmune disorder where the immune system attacks the myelin sheath of nerve fibers in the central nervous system. This results in disrupted communication between the brain and the rest of the body, leading to various neurological symptoms.
Multiple Sclerosis: Multiple sclerosis (MS) is an autoimmune disorder that affects the central nervous system, causing a range of neurological symptoms and disabilities. It is characterized by the immune system attacking and damaging the protective myelin sheath around nerve fibers, leading to disrupted communication between the brain, spinal cord, and the rest of the body.
Myasthenia gravis: Myasthenia gravis is an autoimmune disorder where antibodies attack acetylcholine receptors at the neuromuscular junction, leading to muscle weakness. It primarily affects voluntary muscles, especially those controlling eye and eyelid movement, facial expression, and swallowing.
Nephritis: Nephritis is a type of kidney inflammation that can be caused by an autoimmune response, infection, or other underlying conditions. It is characterized by the body's immune system attacking the kidneys, leading to tissue damage and impaired kidney function.
Ophthalmopathy: Ophthalmopathy is an autoimmune disorder where the immune system attacks the tissues around the eyes, leading to inflammation and swelling. It is commonly associated with Graves' disease.
Pancreas: The pancreas is a glandular organ in the digestive system that produces enzymes and hormones, including insulin. It plays a crucial role in regulating blood sugar levels and aiding digestion.
Pericarditis: Pericarditis is an inflammation of the pericardium, the protective sac surrounding the heart. This condition can cause chest pain, difficulty breathing, and other cardiovascular symptoms, and is often associated with autoimmune disorders.
Peripheral Tolerance: Peripheral tolerance is a state of immunological unresponsiveness or hyporesponsiveness to self-antigens that are present in the periphery, outside of the central lymphoid organs. It is a critical mechanism for maintaining self-tolerance and preventing autoimmune diseases.
Pituitary gland: The pituitary gland is a small, pea-sized gland located at the base of the brain that plays a crucial role in regulating hormones and various physiological processes. It is often referred to as the 'master gland' because it controls other glands in the endocrine system.
Primary adrenal insufficiency (PAI): Primary adrenal insufficiency (PAI) is a disorder where the adrenal glands fail to produce sufficient amounts of steroid hormones, primarily cortisol and aldosterone. This condition commonly results from autoimmune destruction of the adrenal cortex.
Procainamide: Procainamide is a class Ia antiarrhythmic medication used to treat cardiac arrhythmias. It works by blocking sodium channels in the heart, which helps to regulate the heart's electrical activity and prevent abnormal rhythms. Procainamide is particularly relevant in the context of autoimmune disorders, as it can sometimes trigger the development of autoantibodies and lead to drug-induced lupus erythematosus.
Psoriasis: Psoriasis is a chronic autoimmune disorder characterized by the rapid growth of skin cells, leading to thick, red, scaly patches. It involves an abnormal immune response that triggers inflammation and skin cell proliferation.
Psoriatic arthritis: Psoriatic arthritis is a chronic autoimmune disease characterized by inflammation of the skin (psoriasis) and joints (arthritis). It results from an aberrant immune response attacking healthy tissue.
Receptor Editing: Receptor editing is a process in which B lymphocytes modify their antigen receptor genes to produce a different antibody, allowing them to avoid autoreactivity and the development of autoimmune disorders. This process is crucial for maintaining self-tolerance and preventing the immune system from attacking the body's own tissues.
Regulatory T cells: Regulatory T cells (Tregs) are a subset of T lymphocytes that modulate the immune system, maintain tolerance to self-antigens, and prevent autoimmune disease. They play a crucial role in controlling the immune response and preventing excessive inflammation.
Rheumatic Fever: Rheumatic fever is an inflammatory disease that can develop after a streptococcal throat infection. It primarily affects the heart, joints, skin, and brain, and is considered an autoimmune disorder that occurs as a result of the body's immune system mistakenly attacking its own healthy tissues.
Rheumatoid arthritis: Rheumatoid arthritis is a chronic autoimmune disorder characterized by inflammation of the joints, leading to pain and deformity. It occurs when the immune system mistakenly attacks the body's own tissues.
Rheumatoid Arthritis: Rheumatoid arthritis is an autoimmune disorder characterized by chronic inflammation of the joints, leading to pain, stiffness, and progressive joint damage. It is a systemic condition that can affect various organs and tissues throughout the body.
Scleroderma: Scleroderma is a chronic autoimmune disorder characterized by the hardening and thickening of the skin and connective tissues throughout the body. It is a condition where the immune system mistakenly attacks the body's own healthy tissues, leading to excessive production of collagen and fibrosis.
Self-Tolerance: Self-tolerance is the ability of the immune system to recognize and not mount an immune response against the body's own healthy cells and tissues. It is a crucial mechanism that prevents autoimmune diseases by ensuring the immune system does not attack the host's own cells.
Silica Dust: Silica dust refers to small, crystalline particles of silicon dioxide that are generated during various industrial processes. This type of dust is a well-known occupational health hazard that can lead to the development of autoimmune disorders, particularly in individuals with prolonged exposure.
Systemic autoimmune disease: A systemic autoimmune disease is a condition where the immune system mistakenly attacks the body's own tissues, affecting multiple organs or systems. These diseases can lead to chronic inflammation and damage in various parts of the body.
Systemic Lupus Erythematosus: Systemic lupus erythematosus (SLE) is an autoimmune disorder in which the body's immune system mistakenly attacks its own healthy tissues and organs, leading to inflammation and tissue damage throughout the body. It is a chronic, complex condition that can affect various parts of the body, including the skin, joints, kidneys, brain, and other vital organs.
Systemic lupus erythematosus (SLE): Systemic lupus erythematosus (SLE) is a chronic autoimmune disorder where the immune system attacks healthy tissue, causing inflammation and damage to various body systems. It can affect the skin, joints, kidneys, brain, and other organs.
TGF-β: TGF-β, or Transforming Growth Factor-beta, is a multifunctional cytokine that plays a crucial role in various physiological and pathological processes, including inflammation, immune regulation, and autoimmune disorders.
Th1: Th1 cells are a subset of T helper cells that play a crucial role in cell-mediated immunity and the body's defense against intracellular pathogens. They are responsible for activating and coordinating various immune responses, including the activation of macrophages and cytotoxic T cells.
TH1 cells: TH1 cells are a subset of T helper cells that produce cytokines, primarily interferon-gamma (IFN-γ), to activate macrophages and promote cell-mediated immune responses. They play a crucial role in defending against intracellular pathogens like viruses and certain bacteria.
Th17: Th17 cells are a subset of T helper cells that play a crucial role in the immune system's response to autoimmune disorders. They are characterized by their production of the cytokine interleukin-17 (IL-17), which helps coordinate the body's defense against extracellular pathogens and contributes to the development of autoimmune diseases.
Th2: Th2 cells, also known as type 2 helper T cells, are a subset of CD4+ T cells that play a crucial role in the adaptive immune response, particularly in the context of allergic and parasitic infections. These cells are responsible for coordinating and orchestrating various immune functions to combat specific types of pathogens and manage inflammatory responses.
TH2 cells: TH2 cells, also known as T-helper 2 cells, are a subset of CD4+ T cells that play a crucial role in humoral immunity by promoting B cell activation and antibody production. They primarily secrete cytokines like IL-4, IL-5, IL-10, and IL-13.
Thymic selection: Thymic selection is the process by which T cells mature and undergo positive and negative selection in the thymus to ensure self-tolerance and proper immune response. This ensures that only T cells capable of recognizing antigens presented by MHC molecules survive.
Thyroid: The thyroid is a butterfly-shaped gland located in the neck that produces hormones regulating metabolism, growth, and development. It plays a critical role in maintaining physiological homeostasis.
Thyroid stimulating hormone (TSH): Thyroid Stimulating Hormone (TSH) is a pituitary hormone that regulates the production of hormones by the thyroid gland. It plays a crucial role in maintaining metabolic processes and overall endocrine function.
Thyroid-stimulating immunoglobulin (TSI): Thyroid-stimulating immunoglobulin (TSI) is an antibody that mimics thyroid-stimulating hormone (TSH), leading to overstimulation of the thyroid gland. It is commonly associated with Graves' disease, an autoimmune disorder.
Tolerance: Tolerance refers to the immune system's ability to recognize and avoid attacking the body's own cells and tissues. It is essential for preventing autoimmune disorders where the body mistakenly targets its own components.
Toll-like receptors: Toll-like receptors (TLRs) are a class of proteins that play a key role in the innate immune system by recognizing molecules frequently found on pathogens. They help initiate immune responses and bridge innate and adaptive immunity.
Toll-like Receptors: Toll-like receptors (TLRs) are a class of proteins that play a crucial role in the innate immune system's ability to recognize and respond to pathogenic microorganisms. They act as pattern recognition receptors, detecting conserved molecular structures found in various microbes, triggering an immediate immune response.
Transglutinaminase: Transglutaminase is an enzyme that catalyzes the formation of covalent bonds between proteins. It plays a significant role in various biological processes, including blood clotting and skin formation.
Tregs: Tregs, or regulatory T cells, are a specialized subset of T cells that play a crucial role in maintaining immune homeostasis and preventing autoimmune disorders. These cells are essential in regulating the immune response and ensuring that the body's immune system does not attack its own healthy tissues.
TSH-receptor antibody: TSH-receptor antibodies are autoantibodies that target the thyroid-stimulating hormone receptor, often leading to hyperthyroidism. They play a key role in autoimmune thyroid diseases such as Graves' disease.
Type 1 Diabetes: Type 1 diabetes is an autoimmune disorder in which the body's immune system mistakenly attacks and destroys the insulin-producing beta cells in the pancreas, leading to an inability to produce insulin and regulate blood sugar levels effectively.
Type 1 diabetes mellitus: Type 1 diabetes mellitus is an autoimmune disorder where the immune system attacks and destroys insulin-producing beta cells in the pancreas. This leads to high blood glucose levels due to insufficient insulin production.
Type III hypersensitivity: Type III hypersensitivity is an immune reaction where antigen-antibody complexes deposit in tissues, leading to inflammation and tissue damage. It involves immune complex-mediated reactions causing diseases such as systemic lupus erythematosus (SLE) and rheumatoid arthritis.
Vasculitis: Vasculitis is a condition characterized by inflammation of the blood vessels, which can lead to narrowing, weakening, or damage to the vessel walls. This condition is often associated with autoimmune disorders, where the body's immune system mistakenly attacks its own tissues.