Hypersensitivity refers to undesirable (damaging, discomfort-producing and sometimes fatal) reactions produced by the normal immune system. Hypersensitivity reactions require a pre-sensitized (immune) state of the host. The four-group classification was expounded by P. H. G. Gell and Robin Coombs in 1963.^[1] The International Statistical Classification of Diseases and Related Health Problems (most commonly known by the abbreviation ICD) provides codes to classify diseases and a wide variety of signs, symptoms, abnormal findings, complaints, social circumstances and external causes of injury or disease. ... The International Statistical Classification of Diseases and Related Health Problems 10th Revision (ICD-10) is a coding of diseases and signs, symptoms, abnormal findings, complaints, social circumstances and external causes of injury or diseases, as classified by the World Health Organization (WHO). ... // S00-T98 - Injury, poisoning and certain other consequences of external causes (S00-S09) Injuries to the head (S00) Superficial injury of head (S01) Open wound of head (S02) Fracture of skull and facial bones (S03) Dislocation, sprain and strain of joints and ligaments of head (S04) Injury of cranial nerves... The International Statistical Classification of Diseases and Related Health Problems (most commonly known by the abbreviation ICD) provides codes to classify diseases and a wide variety of signs, symptoms, abnormal findings, complaints, social circumstances and external causes of injury or disease. ... The following is a list of codes for International Statistical Classification of Diseases and Related Health Problems. ... The Disease Bold textDatabase is a free website that provides information about the relationships between medical conditions, symptoms, and medications. ... Medical Subject Headings (MeSH) is a huge controlled vocabulary (or metadata system) for the purpose of indexing journal articles and books in the life sciences. ... Philip George Houthem Gell (1914–2001) was an immunologist working in postwar Britain. ... Robert Royston Amos (Robin) Coombs (1921-), British physician and immunologist, co-discoverer of the Coombs test used for testing the presence of antigens (antiglobulins) in Rh disease. ...

Comparison table

Allergy is an abnormal reaction to a substance foreign to the body that is acquired, predictable and rapid. ... Eczema-a typical atopic manifestation Atopy (Greek ατοπία - placelessness) or atopic syndrome is an allergic hypersensitivity affecting parts of the body not in direct contact with the allergen. ... Anaphylaxis is an acute systemic (multi-system) and severe Type I Hypersensitivity allergic reaction in humans and other mammals. ... Immunoglobulin E (IgE) is an antibody subclass (known as isotypes), found only in mammals. ... Erythroblastosis fetalis, also known as hemolytic disease of the newborn is a condition that develops in a fetus when antibodies produced by the mother attack the fetuss red blood cells. ... Goodpasture’s syndrome (also known as Goodpasture’s disease and anti-glomerular basement membrane disease or anti-GBM disease) was first described by Ernest Goodpasture in 1919. ... Autoimmune hemolytic anemia (AIHA) is one type of hemolytic anemias caused by excessive hemolyisis and it is identified by auto-antibodies that react with RBCs. ... IgM (Immunglobulin M) antibody molecule consisting of 5 base units. ... Molecular surface of an IgG molecule Immunoglobulin G(IgG) is a monomeric immunoglobulin, built of two heavy chains γ and two light chains. ... A complement protein attacking an invader. ... Serum sickness is a reaction to an antiserum derived from an animal source. ... Arthus reaction is a type III hypersensitivity reaction. ... Lupus erythematosus (also known as systemic lupus erythematosus - SLE) is an autoimmune disorder in which antibodies are created against the patients own DNA. It classically presents with a butterfly-shaped malar rash, causing a wolf-like appearance (Lupus is Latin for wolf). ... Molecular surface of an IgG molecule Immunoglobulin G(IgG) is a monomeric immunoglobulin, built of two heavy chains γ and two light chains. ... A complement protein attacking an invader. ... Contact dermatitis is a term for a skin reaction resulting from exposure to allergens or irritants. ... Tuberculosis (abbreviated as TB for tubercle bacillus or Tuberculosis) is a common and deadly infectious disease caused by mycobacteria, mainly Mycobacterium tuberculosis. ... Cell-mediated immunity is an immune response that does not involve antibodies but rather involves the activation of macrophages and NK-cells, the production of antigen-specific cytotoxic T-lymphocytes, and the release of various cytokines in response to an antigen. ...

Type 1 - immediate (or atopic, or anaphylactic)

Main article: Allergy

Type 1 hypersensitivity is an allergic reaction provoked by reexposure to a specific type of antigen referred to as an allergen.^[3] Exposure may be by ingestion, inhalation, injection, or direct contact. The difference between a normal immune response and a type I hypersensitive response is that plasma cells secrete IgE. This class of antibodies binds to Fc receptors on the surface of tissue mast cells and blood basophils. Mast cells and basophils coated by IgE are "sensitized." Later exposure to the same allergen, cross-links the bound IgE on sensitized cells resulting in degranulation and the secretion of pharmacologically active mediators such as mastcell- leukotriene, and prostaglandin that act on the surrounding tissues. The principal effects of these products are vasodilation and smooth-muscle contraction. Allergy is an abnormal reaction to a substance foreign to the body that is acquired, predictable and rapid. ... An antigen or immunogen is a molecule that stimulates an immune response. ... In general terms, eating (formally, ingestion) is the process of consuming something edible, i. ... An injection is a method of putting liquid into the body with a hollow needle and a syringe which is pierced through the skin to a sufficient depth for the material to be forced into the body. ... IGE (Internet Gaming Entertainment) is the largest MMORPG services company world-wide, with offices in Los Angeles, Hong Kong, and Miami. ... The degranulation process in a Mast cell. ... Leukotrienes are autocrine and paracrine eicosanoid lipid mediators derived from arachidonic acid by 5-lipoxygenase. ... E1 - Alprostadil I2 - Prostacyclin A prostaglandin is any member of a group of lipid compounds that are derived enzymatically from fatty acids and have important functions in the animal body. ... The blood vessels are part of the circulatory system and function to transport blood throughout the body. ...

The reaction may be either local or systemic. Symptoms vary from mild irritation to sudden death from anaphylactic shock. Treatment usually involves epinephrine, antihistamines, and corticosteroids. If the entire body gets involved, then anaphylaxis can take place; an acute, systemic reaction that can prove fatal. Anaphylaxis is an acute systemic (multi-system) and severe Type I Hypersensitivity allergic reaction in humans and other mammals. ... Adrenaline redirects here. ... An antihistamine is a drug which serves to reduce or eliminate effects mediated by histamine, an endogenous chemical mediator released during allergic reactions, through action at the histamine receptor. ... In physiology, corticosteroids are a class of steroid hormones that are produced in the adrenal cortex. ...

Some examples:

• Allergic asthma
• Allergic conjunctivitis
• Allergic rhinitis ("hay fever")
• Anaphylaxis
• Angioedema
• Urticaria (hives)
• Eosinophilia
• Penicillin
• Cephalosporin

For the play, see Hay Fever. ... Angioedema (BE: angiooedema), also known by its eponym Quinckes edema, is the rapid swelling (edema) of the skin, mucosa and submucosal tissues. ... Eosinophilia is the state of having high eosinophil granulocytes in the blood. ... Penicillin core structure Penicillin (abbreviated PCN) is a group of β-lactam antibiotics used in the treatment of bacterial infections caused by susceptible, usually Gram-positive, organisms. ... The cephalosporins, are a class of β-lactam antibiotics. ...

Type 2 - antibody-dependent

In type 2 hypersensitivity, the antibodies produced by the immune response bind to antigens on the patient's own cell surfaces. The antigens recognized in this way may either be intrinsic ("self" antigen, innately part of the patient's cells) or extrinsic (absorbed onto the cells during exposure to some foreign antigen, possibly as part of infection with a pathogen). These cells are recognized by macrophages or dendritic cells which act as antigen presenting cells, this causes a B cell response where antibodies are produced against the foreign antigen. A macrophage of a mouse stretching its arms to engulf two particles, possibly pathogens Macrophages (Greek: big eaters, from makros large + phagein eat) are cells within the tissues that originate from specific white blood cells called monocytes. ... Dendritic cells (DC) are immune cells and form part of the mammal immune system. ... B cells are lymphocytes that play a large role in the humoral immune response (as opposed to the cell-mediated immune response). ...

An example here is the reaction to penicillin where the drug can bind to red blood cells causing them to be recognised as different, B cell proliferation will take place and antibodies to the drug are produced. IgG and IgM antibodies bind to these antigens to form complexes that activate the classical pathway of complement activation to eliminate cells presenting foreign antigens (which are usually, but not in this case, pathogens). That is, mediators of acute inflammation are generated at the site and membrane attack complexes cause cell lysis and death. The reaction takes hours to a day. Schematic of antibody binding to an antigen An antibody is a protein complex used by the immune system to identify and neutralize foreign objects like bacteria and viruses. ... IGM might be an acronym or abbreviation for: The polymeric immunoglobulin, IgM International Grandmaster, a chess ranking intergalactic medium Intragroup medium - see: Intracluster medium IG Metall - the dominant German metalworkers union IGM is an acronym created by Robinson Technologies for several early BBS door games, including Legend of the Red... This article may be too technical for most readers to understand. ... A complement protein attacking an invader. ... The membrane attack complex (MAC) is formed on the surface of intruding pathogenic bacterial cells as a result of the activation of the complement system, and it is one of the ultimate weapons of the immune system. ... This article is about the biological definition of the word Lysis. ...

Another form of type 2 hypersensitivity is called antibody-dependent cell-mediated cytotoxicity (ADCC). Here, cells exhibiting the foreign antigen are tagged with antibodies (IgG or IgM). These tagged cells are then recognised by natural killer (NK) cells and macrophages (recognised via IgG bound (via the Fc region) to the effector cell surface receptor, CD16 (FcγRIII)), which in turn kill these tagged cells. NK cells are responsible for antibody-dependent cellular cytotoxicity (ADCC). ... CD16 is a Fc receptor. ...

Some examples:

• Autoimmune hemolytic anemia
• Goodpasture's syndrome
• Pemphigus
• Pernicious anemia (if autoimmune)
• Immune thrombocytopenia
• Transfusion reactions
• Graves disease (see type V below)
• Myasthenia gravis (see type V below)
• Rheumatic fever
• Hemolytic disease of the newborn (erythroblastosis fetalis)
• Acute transplant rejection

This article discusses the medical condition. ... Goodpasture’s syndrome (also known as Goodpasture’s disease and anti-glomerular basement membrane disease or anti-GBM disease) was first described by Ernest Goodpasture in 1919. ... Pemphigus is an autoimmune disorder that causes blistering and raw sores on skin and mucous membranes. ... Pernicious anemia (also known as Biermers anaemia or Addisons anaemia or Addison-Biermer anaemia) is a form of megaloblastic anaemia due to vitamin B12 deficiency dependent on impaired absorption of vitamin B12 in the setting of atrophic gastritis, and more specifically of loss of gastric parietal cells. ... Thrombocytopenia (or -paenia, or thrombopenia in short) is the presence of relatively few platelets in blood. ... Blood transfusion is the process of transferring blood or blood-based products from one person into the circulatory system of another. ... Graves disease is a thyroid disorder characterized by goiter, exophthalmos, orange-peel skin, and hyperthyroidism. ... Myasthenia gravis (sometimes abbreviated MG; from the Greek myastheneia, lit. ... Rheumatic fever is an inflammatory disease which may develop after a Group A streptococcal infection (such as strep throat or scarlet fever) and can involve the heart, joints, skin, and brain. ... Hemolytic disease of the newborn, also known as HDN, is an alloimmune condition that develops in a fetus, when the IgG antibodies that have been produced by the mother and have passed through the placenta include ones which attack the red blood cells in the fetal circulation. ...

Type 3 - immune complex

Type 3 hypersensitivity occurs when antigens and antibodies are present in roughly equal amounts, causing extensive cross-linking. Large immune complexes that cannot be cleared are deposited in vessel walls and induce an inflammatory response. The reaction can take hours, days, or even weeks to develop.

Some clinical examples:

• Rheumatoid arthritis
• Immune complex glomerulonephritis
• Serum sickness
• Subacute bacterial endocarditis
• Symptoms of malaria
• Systemic lupus erythematosus
• Arthus reaction
• Farmer's lung (Arthus-type reaction)
• Polyarteritis nodosa

Rheumatoid arthritis (RA) is traditionally considered a chronic, inflammatory autoimmune disorder that causes the immune system to attack the joints. ... Glomerulonephritis, also known as glomerular nephritis and abbreviated GN, is a primary or secondary immune-mediated renal disease characterized by inflammation of the glomeruli, or small blood vessels in the kidneys. ... Serum sickness is a reaction to an antiserum derived from an animal source. ... Endocarditis is an inflammation of the inner layer of the heart, the endocardium. ... Malaria is a vector-borne infectious disease caused by protozoan parasites. ... Arthus reaction is a type III hypersensitivity reaction. ... This article or section does not adequately cite its references or sources. ... Polyarteritis nodosa (or periarteritis nodosa) is a serious blood vessel disease. ...

Type 4 - cell-mediated (delayed-type hypersensitivity, DTH)

See also: Cell mediated immunity

Type 4 hypersensitivity is often called delayed type as the reaction takes two to three days to develop. Unlike the other types, it is not antibody mediated but rather is a type of cell-mediated response. Cell-mediated immunity is an immune response that does not involve antibodies but rather involves the activation of macrophages and NK-cells, the production of antigen-specific cytotoxic T-lymphocytes, and the release of various cytokines in response to an antigen. ...

CD8+ cytotoxic T cells and CD4+ helper T cells recognize antigen in a complex with either type 1 or 2 major histocompatibility complex. The antigen-presenting cells in this case are macrophages which secrete IL-12, which stimulates the proliferation of further CD4+ T cells. CD4+ T cells secrete IL-2 and interferon gamma, further inducing the release of other Type 1 cytokines, thus mediating the immune response. Activated CD8+ T cells destroy target cells on contact while activated macrophages produce hydrolytic enzymes and, on presentation with certain intracellular pathogens, transform into multinucleated giant cells. A cytotoxic T cell (also known as TC, CTL or killer T cell) belongs to a sub-group of T lymphocytes (a type of white blood cell) which are capable of inducing the death of infected somatic or tumor cells; they kill cells that are infected with viruses (or other... A helper (or TH) T cell is a T cell (a type of white blood cell) which has on its surface antigen receptors that can bind to fragments of antigens displayed by the Class II MHC molecules found on professional antigen-presenting cells (APCs). ... Protein images comparing the MHC I (1hsa) and MHC II (1dlh) molecules. ... Interleukin 12 (IL-12) is an interleukin that are naturally produced by macrophages and human B-lymphoblastoid cells (NC-37)in response to antigenic stimulation. ... The abbreviation IL-2 can refer to: Interleukin-2, a cytokine responsible for stimulating the growth of T-lymphocytes. ... Interferons (IFNs) are natural proteins produced by the cells of the immune system of most vertebrates in response to challenges by foreign agents such as viruses, bacteria, parasites and tumor cells. ... Hydrolytic enzymes break down protein, carbohydrate, and fat molecules into their simplest units. ... Ribbon diagram of the enzyme TIM, surrounded by the space-filling model of the protein. ... Large cell is a term used in oncology. ...

Some clinical examples:

• Contact dermatitis (poison ivy rash, for example)
• Atopic dermatitis (eczema)
• Temporal arteritis
• Hashimoto's thyroiditis
• Symptoms of leprosy
• Symptoms of tuberculosis
• Mantoux test
• Coeliac disease
• Chronic transplant rejection

Contact dermatitis is a term for a skin reaction resulting from exposure to allergens or irritants. ... Poison ivy redirects here. ... Temporal arteritis, also called giant cell arteritis (GCA) is an inflammatory disease of blood vessels (most commonly large and medium arteries of the head). ... Hashimotos thyroiditis or chronic lymphocytic thyroiditis is an autoimmune disease where the bodys own antibodies attack the cells of the thyroid. ... For the malady found in the Hebrew Bible, see Tzaraath. ... Tuberculosis (abbreviated as TB for tubercle bacillus or Tuberculosis) is a common and deadly infectious disease caused by mycobacteria, mainly Mycobacterium tuberculosis. ... The Mantoux skin test consists of an intradermal injection of exactly one tenth of a milliliter (mL) of PPD tuberculin. ... Coeliac disease (pronounced ), also spelt celiac disease, is an autoimmune disorder of the small bowel that occurs in genetically predisposed people of all ages from middle infancy. ...

Type 5 - stimulatory

This is an additional type that is sometimes (often in Britain) used as a distinction from Type 2.^[4]

Instead of binding to cell surface components, the antibodies recognize and bind to the cell surface receptors, which either prevents the intended ligand binding with the receptor or mimics the effects of the ligand, thus impairing cell signalling. In biochemistry, a receptor is a protein on the cell membrane or within the cytoplasm or cell nucleus that binds to a specific molecule (a ligand), such as a neurotransmitter, hormone, or other substance, and initiates the cellular response to the ligand. ... In chemistry, a ligand is an atom, ion, or molecule (see also: functional group) that generally donates one or more of its electrons through a coordinate covalent bond to, or shares its electrons through a covalent bond with, one or more central atoms or ions (these ligands act as a...

Some clinical examples:

• Graves disease
• Myasthenia gravis

(There is also a type 6 hypersensitivity reaction in which natural killer cells lyse cells that have been coated in antibody and this reaction is thought to be implicated with certain autoimmune diseases, tumour rejection and parasite rejection.) Graves disease is a thyroid disorder characterized by goiter, exophthalmos, orange-peel skin, and hyperthyroidism. ... Myasthenia gravis (sometimes abbreviated MG; from the Greek myastheneia, lit. ...

See also

• Allergy

Allergy is an abnormal reaction to a substance foreign to the body that is acquired, predictable and rapid. ...

References

1. ^ Gell PGH, Coombs RRA, eds. Clinical Aspects of Immunology. 1st ed. Oxford, England: Blackwell; 1963.
2. ^ ^{a b c} Unless else specified in boxes, then ref is: Lippincott's Illustrated Reviews: Immunology. Paperback: 384 pages. Publisher: Lippincott Williams & Wilkins; (July 1, 2007). Language: English. ISBN-10: 0781795435. ISBN-13: 978-0781795432. Page 195
3. ^ med/1101 at eMedicine
4. ^ Rajan TV. The Gell-Coombs classification of hypersensitivity reactions: a re-interpretation. Trends Immunol. 2003 Jul;24(7):376-9. PMID 12860528

eMedicine is an online clinical medical knowledge base that was founded in 1996. ...

External links

• -529858552 at GPnotebook
• ENT46 at FPnotebook