Hypersensitivity

For other uses, see Hypersensitivity (disambiguation).

Hypersensitivity
Classification and external resources
Specialty	Allergy and immunology
ICD-10	T78.4
ICD-9-CM	995.3
DiseasesDB	28827
MeSH	D006967

Hypersensitivity (also called hypersensitivity reaction or intolerance) is a set of undesirable reactions produced by the normal immune system, including allergies and autoimmunity. They are usually referred to as an over- reaction of the immune system and these reactions may be damaging, uncomfortable, or occasionally fatal. Hypersensitivity reactions require a pre-sensitized (immune) state of the host. They are classified in four groups after the proposal of P. G. H. Gell and Robin Coombs in 1963.^[1]

Coombs and Gell classification

Comparison of hypersensitivity types
Type	Alternative names	Often mentioned disorders	Mediators	Description	Video explanation
I	Allergy (immediate)	Atopy Anaphylaxis Asthma	IgE	Fast response which occurs in minutes, rather than multiple hours or days. Free antigens cross link the IgE on mast cells and basophils which causes a release of vasoactive biomolecules. Testing can be done via skin test for specific IgE.^[2]	Video explanation of type I hypersensitivity
II	Cytotoxic, antibody-dependent	Autoimmune hemolytic anemia Rheumatic heart disease Thrombocytopenia Erythroblastosis fetalis Goodpasture's syndrome Graves' disease see type V explanation below Myasthenia gravis see type V explanation below	IgM or IgG (Complement) MAC	Antibody (IgM or IgG) binds to antigen on a target cell, which is actually a host cell that is perceived by the immune system as foreign, leading to cellular destruction via the MAC. Testing includes both the direct and indirect Coombs test.^[3]	Video explanation of type II hypersensitivity
III	Immune complex disease	Serum sickness Arthus reaction Rheumatoid arthritis Post streptococcal glomerulonephritis Membranous nephropathy Lupus nephritis Systemic lupus erythematosus Extrinsic allergic alveolitis (hypersensitivity pneumonitis)	IgG (Complement) Neutrophils	Antibody (IgG) binds to soluble antigen, forming a circulating immune complex. This is often deposited in the vessel walls of the joints and kidney, initiating a local inflammatory reaction.^[4]	Video explanation of type III hypersensitivity
IV	Delayed-type hypersensitivity,^[2]^[3] cell-mediated immune memory response, antibody-independent	Contact dermatitis, including Urushiol-induced contact dermatitis (poison ivy rash). Mantoux test Chronic transplant rejection Multiple sclerosis^[5]	T-cells	Helper T cells (specifically Th1 helper t cells) are activated by an antigen presenting cell. When the antigen is presented again in the future, the memory Th1 cells will activate macrophages and cause an inflammatory response. This ultimately can lead to tissue damage.^[6]	Video explanation of type IV hypersensitivity
V	Autoimmune disease, receptor mediated (see below)	Graves' disease Myasthenia gravis	IgM or IgG (Complement)

Type V

This is an additional type that is sometimes (often in the UK) used as a distinction from Type 2.^[7]

Instead of binding to cell surfaces, the antibodies recognise 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 signaling.

Some clinical examples:

The use of Type 5 is rare. These conditions are more frequently classified as Type 2, though sometimes they are specifically segregated into their own subcategory of Type 2.

References

↑ Gell PGH, Coombs RRA, eds. Clinical Aspects of Immunology. 1st ed. Oxford, England: Blackwell; 1963. Section IV, Chapter 1
1 2 Black, C. A. (1999). "Delayed type hypersensitivity: Current theories with an historic perspective". Dermatology Online Journal. 5 (1): 7. PMID 10673450.
1 2 Delayed Hypersensitivity Reactions at eMedicine
↑ Kumar, Vinay; Abbas, Abul K.; Aster, Jon C., eds. (2014). "Hypersensitivity: Immunologicaly Mediated Tissue Injury". Robbins & Cotran Pathologic Basis of Disease (9th ed.). Elsevier Health Sciences. pp. 200–11. ISBN 978-0-323-29635-9.
↑ Mitchell, Richard Sheppard; Kumar, Vinay; Abbas, Abul K.; Fausto, Nelson (2007). "Table 5-1". Robbins Basic Pathology (8th ed.). Philadelphia: Saunders. ISBN 1-4160-2973-7.
↑ Le, Tau. First Aid for the USMLE Step 1 2013, p. 203-204
↑ Rajan, T.V. (2003). "The Gell–Coombs classification of hypersensitivity reactions: A re-interpretation". Trends in Immunology. 24 (7): 376–9. doi:10.1016/S1471-4906(03)00142-X. PMID 12860528.

External links

Hypersensitivity reactions at GPnotebook

Consequences of external causes (T66–T78, 990–995)

Temperature/radiation	elevated temperature Hyperthermia Heat syncope reduced temperature Hypothermia Immersion foot syndromes Trench foot Tropical immersion foot Warm water immersion foot Chilblains Frostbite Aerosol burn Cold intolerance Acrocyanosis Erythrocyanosis crurum radiation Radiation poisoning Radiation burn Chronic radiation keratosis Eosinophilic, polymorphic, and pruritic eruption associated with radiotherapy Radiation acne Radiation cancer Radiation recall reaction Radiation-induced erythema multiforme Radiation-induced hypertrophic scar Radiation-induced keloid Radiation-induced morphea

Air	Hypoxia/Asphyxia Barotrauma Aerosinusitis Decompression sickness High altitude Altitude sickness Chronic mountain sickness HAPE HACE

Food	Starvation

Maltreatment	Physical abuse Sexual abuse Psychological abuse

Travel	Motion sickness Seasickness Airsickness Space adaptation syndrome

Adverse effect	Hypersensitivity Anaphylaxis Angioedema Allergy Arthus reaction Adverse drug reaction

Other	Electric shock Drowning Lightning injury

Ungrouped skin conditions resulting from physical factors	Dermatosis neglecta Pinch mark Pseudoverrucous papules and nodules Sclerosing lymphangiitis Tropical anhidrotic asthenia UV-sensitive syndrome environmental skin conditions Electrical burn frictional/traumatic/sports Black heel and palm Equestrian perniosis Jogger's nipple Pulling boat hands Runner's rump Surfer's knots Tennis toe Vibration white finger Weathering nodule of ear Wrestler's ear Coral cut Painful fat herniation Uranium dermatosis iv use Skin pop scar Skin track Slap mark Pseudoacanthosis nigricans Narcotic dermopathy

Immune disorders: Lymphoid and complement immunodeficiency (D80–D85, 279.0–4)

Primary

Antibody/humoral (B)

Hypogammaglobulinemia	X-linked agammaglobulinemia Transient hypogammaglobulinemia of infancy

Dysgammaglobulinemia	IgA deficiency IgG deficiency IgM deficiency Hyper IgM syndrome (1 2 3 4 5) Wiskott-Aldrich syndrome Hyper-IgE syndrome

Other	Common variable immunodeficiency ICF syndrome

T cell deficiency (T)

thymic hypoplasia: hypoparathyroid (Di George's syndrome)
euparathyroid (Nezelof syndrome
Ataxia telangiectasia)

peripheral: Purine nucleoside phosphorylase deficiency

Hyper IgM syndrome (1)

Severe combined (B+T)

x-linked: X-SCID
autosomal: Adenosine deaminase deficiency
Omenn syndrome
ZAP70 deficiency
Bare lymphocyte syndrome

Acquired

AIDS

Leukopenia:
Lymphocytopenia

Idiopathic CD4+ lymphocytopenia

Complement deficiency

Hypersensitivity and autoimmune diseases (279.5–6)

Type I/allergy/atopy
(IgE)

Foreign	Atopic eczema Allergic urticaria Allergic rhinitis (Hay fever) Allergic asthma Anaphylaxis Food allergy common allergies include: Milk Egg Peanut Tree nut Seafood Soy Wheat Penicillin allergy

Autoimmune	Eosinophilic esophagitis

Type II/ADCC

- IgM
- IgG

Foreign

Hemolytic disease of the newborn

Autoimmune

Cytotoxic	Autoimmune hemolytic anemia Immune thrombocytopenic purpura Bullous pemphigoid Pemphigus vulgaris Rheumatic fever Goodpasture's syndrome Guillain–Barré syndrome

"Type V"/receptor	Graves' disease Myasthenia gravis Pernicious anemia

Type III
(Immune complex)

Foreign	Henoch–Schönlein purpura Hypersensitivity vasculitis Reactive arthritis Farmer's lung Post-streptococcal glomerulonephritis Serum sickness Arthus reaction

Autoimmune	Systemic lupus erythematosus Subacute bacterial endocarditis Rheumatoid arthritis

Type IV/cell-mediated
(T cells)

Foreign	Allergic contact dermatitis Mantoux test

Autoimmune	Diabetes mellitus type 1 Hashimoto's thyroiditis Multiple sclerosis Coeliac disease Giant-cell arteritis Postorgasmic illness syndrome Reactive arthritis

GVHD	Transfusion-associated graft versus host disease

Unknown/
multiple

Foreign	Hypersensitivity pneumonitis Allergic bronchopulmonary aspergillosis Transplant rejection Latex allergy (I+IV)

Autoimmune	Sjögren's syndrome Autoimmune hepatitis Autoimmune polyendocrine syndrome APS1 APS2 Autoimmune adrenalitis Systemic autoimmune disease

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Hypersensitivity

Coombs and Gell classification

Type V

See also

References

External links