I. Definition

  1. Categories of Hypersensitivity Response

II. Type 1: Immediate Hypersensitivity Reaction

  1. Mediated by IgE Antibody to specific antigens
    1. Mast cells stimulated and release histamine
  2. Reaction within one hour of exposure
  3. Examples
    1. Anaphylaxis (e.g. Penicillin)
    2. Urticaria
    3. Angioedema
    4. Atopic Allergy

III. Type 2: Cytotoxic Antibody Reaction

  1. Mediated by IgG and IgM to specific antigens
  2. Examples
    1. Transfusion Reaction
    2. Rhesus Incompatibility (Rh Incompatibility)
    3. Mycoplasma pneumoniae related cold agglutinins
    4. Hashimoto' Thyroiditis
    5. Goodpasture's Syndrome
    6. Delayed transplant graft rejection

IV. Type 3: Immune Complex Reaction

  1. Antigen-Antibody complexes deposit in tissue
  2. Reaction within 1-3 weeks after exposure
  3. Examples
    1. Systemic Lupus Erythematosus
    2. Erythema Nodosum
    3. Polyarteritis Nodosa
    4. Arthus Reaction (e.g. Farmer's Lung)
    5. Rheumatoid Arthritis
    6. Elephantiasis (Wuchereria bancrofti reaction)
    7. Jarisch-Herxheimer Reaction
    8. Serum Sickness

V. Type 4: Delayed-Type Hypersensitivity

  1. Mediated by T-Lymphocytes to specific antigens
    1. Involves major histocompatibility complex (MHC)
    2. Reaction within 2-7 days after exposure
  2. Examples
    1. Mantoux Test (PPD)
    2. Allergic Contact Dermatitis (e.g. Nickel allergy)

VI. Other allergy mediated reactions

  1. Stimulatory Hypersensitivity
    1. Humoral Antibody activates receptor sites
    2. Example: Thyrotoxicosis (TSH autoantibodies)
  2. Fas/Fas Ligand-induced apoptosis
    1. Example: Stevens Johnson Syndrome
  3. T-Cell activation
    1. Example: Sulfonamide induced Morbilliform rash

VII. References

  1. Roitt (1988) Essential Immunology, Blackwell,p. 193-214
  2. Riedl (2003) Am Fam Physician 68:1781-90 [PubMed] (or open in [QxMD Read])

Images: Related links to external sites (from Google)

Ontology: Hypersensitivity (C0020517)

Definition (ICF) Functions of the body's response of increased sensitization to foreign substances, such as in sensitivities to different antigens.
Definition (ICF-CY) Functions of the body's response of increased sensitization to foreign substances, such as in sensitivities to different antigens.
Definition (NCI) A local or general reaction of an organism following contact with a specific allergen to which it has been previously exposed and to which it has become sensitized.
Definition (SNOMEDCT) Known to have allergic reactions to particular substance(s)
Definition (NCI) A disorder characterized by an adverse local or general response from exposure to an allergen.
Definition (NCI) Hypersensitivity; a local or general reaction of an organism following contact with a specific allergen to which it has been previously exposed and to which it has become sensitized.
Definition (MEDLINEPLUS)

An allergy is a reaction of your immune system to something that does not bother most other people. People who have allergies often are sensitive to more than one thing. Substances that often cause reactions are

How do you get allergies? Scientists think both genes and the environment have something to do with it. Normally, your immune system fights germs. It is your body's defense system. In most allergic reactions, however, it is responding to a false alarm.

Allergies can cause a runny nose, sneezing, itching, rashes, swelling or asthma. Symptoms vary. Although allergies can make you feel bad, they usually won't kill you. However, a severe reaction called anaphylaxis is life-threatening.

NIH: National Institute of Allergy and Infectious Diseases

Definition (MSH) Altered reactivity to an antigen, which can result in pathologic reactions upon subsequent exposure to that particular antigen.
Definition (CSP) state of previously immunized body in which tissue damage results from the immune response to a further dose of antigen.
Definition (HL7V3.0) <p>Hypersensitivity to an agent caused by an immunologic response to an initial exposure</p>
Definition (NCI) An exaggerated response by the immune system to a drug or other substance.
Definition (GO) An inflammatory response to an exogenous environmental antigen or an endogenous antigen initiated by the adaptive immune system. [GOC:jal, ISBN:0781735149 "Fundamental Immunology"]
Concepts Pathologic Function (T046)
MSH D006967
ICD10 T78.4 , T78.40
SnomedCT 421961002, 419076005, 418925002, 91232002, 418168000, 127072000, 421668005, 106190000, 212998004, 157758001, 274211000, 269284003, 257550005, 21957007, 157754004, 269432007, 282092005, 212999007, 418634005
English Allergies, Allergy, Hypersensitivities, Hypersensitivity, Allergy, unspecified, ALLERGIC REACTION, ALLERGIC REACTION (NOS), ALLERGY, HYPERSENSITIVITY, REACTION ALLERGIC (NOS), Allergic reaction, NOS, Allergic state, NOS, Allergy, NOS, HYPERSENSITIVITY REACTION (NOS), Hypersensitivity reaction, NOS, REACTION HYPERSENSITIVITY (NOS), Allergy/allergic react NOS, Allergy/allergic reaction NOS, Hypersensitivity reaction, Allergic reaction, Allergic disorder, Hypersensitivity (finding), Allergic disorder (disorder), Allergy (disorder), Disorder due to allergic reaction (disorder), Disorder due to allergic reaction, Disorder due to immune hypersensitivity reaction, Hypersensitivity reaction (disorder), Immune hypersensitivity disorder (disorder), Immune hypersensitivity disorder, Allergic state (disorder), HYSN, ALLERGIC/HYPERSENSITIVITY, Allergic reaction NOS, Allergy disorder, hypersensitivity, hypersensitivity (symptom), allergic reaction, allergic reaction (diagnosis), (Allergy, unspecified) or (hypersensitivity NOS) (disorder), Allergic reaction NOS (disorder), Allergic reaction (NOS), Reaction allergic (NOS), Allergy NOS, Hypersensitivity NOS, Hypersensitivity reaction (NOS), Reaction hypersensitivity (NOS), Hypersensitivity symptom, Hypersensitivity reactions, Allergy, unspecified (disorder), Allergic reactions, Hypersensitivity [Disease/Finding], Allergy., allergy disorders, hypersensitivity reactions, allergic disorder, allergic disorders, hypersensitivity symptoms, hypersensitivity symptom, allergies, allergic reactions, hypersensitivities, hypersensitivity reaction, allergic response, Allergic state, Hypersensitivity (qualifier value), Atopic AND/OR hypersensitivity state, Allergy/allergic reaction nos, allergy, hypersensitivity; reaction, allergic; reaction, reaction; allergic, reaction; hypersensitivity, (Allergy, unspecified) or (hypersensitivity NOS), Allergic Disorders, Allergic reaction to substance, Immune hypersensitivity reaction (disorder), Allergic reaction (disorder), Allergic reaction to substance (disorder), Immune hypersensitivity reaction
French HYPERSENSIBILITE, ALLERGIE, Réaction d'hypersensibilité, Réaction allergique, Allergie SAI, Hypersensibilité SAI, Réaction allergique SAI, Réaction d'hypersensibilité SAI, HYSN, Symptôme d'hypersensibilité, Allergie/reaction allergique NP, REACTION ALLERGIQUE, Allergie, Hypersensibilité
Portuguese HIPERSENSIBILIDADE, ALERGIA, Sintoma de hipersensibilidade, Reacção alérgica NE, Reacção alérgica, Hipersensibilidade NE, Alergia NE, Reacção de hipersensibilidade, Reacção de hipersensibilidade NE, Alergia/reaccao alergica NE, REACCAO ALERGICA, Reação Alérgica, Alergia, Hipersensibilidade
Spanish HIPERSENSIBILIDAD, ALERGIA, reacción alérgica a una sustancia (trastorno), reacción alérgica a una sustancia, reacción por hipersensibilidad inmunológica (trastorno), reacción por hipersensibilidad inmunológica, trastorno inmunológico por hipersensibilidad, reacción de hipersensibilidad (trastorno), reacción de hipersensibilidad, estado alérgico (trastorno), trastorno debido a reacción alérgica, trastorno por reacción inmunológica por hipersensibilidad, Reacción alérgica, Reacción de hipersensibilidad (NEOM), Alergia NEOM, Hipersensibilidad NEOM, Síntoma de hipersensibilidad, Reacción alérgica NEOM, Reación de hipersensibilidad, Reacción de hipersensibilidad, Reacción alérgica (NEOM), trastorno alérgico, trastorno causado por reacción alérgica (trastorno), hipersensibilidad (hallazgo), trastorno por reacción alérgica, reacción de hipersensibilidad inmunológica (trastorno), reacción alérgica (trastorno), trastorno alérgico (trastorno), alergia (trastorno), trastorno causado por reacción alérgica, reacción alérgica, Allergic reaction NOS, (Allergy, unspecified) or (hypersensitivity NOS), Allergy, unspecified, Hypersensitivity NOS, Alergia/reaccion alergica NE, REACCION ALERGICA, trastorno de hipersensibilidad inmunológica, trastorno de hpersensibilidad inmunológica (trastorno), trastorno de hipersensibilidad inmunológica (trastorno), trastorno de hpersensibilidad inmunológica, Reaccion Alergica, Reacción Alérgica, alergia, no especificada (trastorno), alergia, no especificada, alergia, estado alérgico, estado atópico Y/O de hipersensibilidad, hipersensibilidad (calificador), hipersensibilidad, reacción alérgica, SAI (trastorno), reacción alérgica, SAI, Alergia, Hipersensibilidad
German ALLERGIE, allergische Reaktion NNB, Uebersensibilitaetsreaktion, HYSN, Reaktion, allergisch (NNB), Ueberempfindlichkeit NNB, Uebersensibilitaetsreaktion (NNB), allergische Reaktion, allergische Reaktion (NNB), Uebersensibilitaetssymptom, Allergie NNB, ALLERGISCHE REAKTION, Allergie, nicht naeher bezeichnet, Allergie/anaphylakt Schock NNB, HYPERSENSIBILITAET, Ueberempfindlichkeit, Allergie, Hypersensitivität, Überempfindlichkeit
Dutch allergische reactie NAO, reactie allergisch (NAO), overgevoeligheidsreactie, allergische reactie (NAO), overgevoeligheid NAO, overgevoeligheidsreactie (NAO), allergie, reactie overgevoeligheid (NAO), hypersensitiviteitssymptoom, HYSN, allergie NAO, allergische reactie, Allergie/allergische reactie NAO, Allergie/allergische reactie nao, allergisch; reactie, overgevoeligheid; reactie, reactie; allergisch, reactie; overgevoeligheid, Allergie, niet gespecificeerd, overgevoeligheid, Allergie, Overgevoeligheid
Italian Sintomo di ipersensibilità, Reazione da ipersensibilità (non specificata), Allergia, Allergia NAS, Reazione da ipersensibilità, Reazione di ipersensibilità (NAS), Reazione allergica, Reazione allergica (NAS), Reazione allergica NAS, Ipersensibilità NAS, Allergia (Specifica), Allergia/reaz allergica NSA, Ipersensibilità
Japanese アレルギー反応, 過敏症状, 過敏症反応(NOS), 過敏症NOS, アレルギー反応(NOS), アレルギー反応NOS, アレルギーNOS, 過敏症反応, アレルギーNOS, カビンショウハンノウNOS, アレルギーハンノウNOS, カビンショウジョウ, カビンショウハンノウ, カビンショウNOS, カビンショウ, アレルギーハンノウ, アレルギー, アレルギー, 過敏症
Danish Allergi/allergisk reaktion INA
Hungarian allergia/nem megh.allerg.reakcio, allergiás reakció, allergia k.m.n., Hypersensitivitási tünet, allergiás reakció (k.m.n.), HSYN, Allergiás reakció (k.m.n.), Túlérzékenységi reakció (k.m.n.), Hypersensitivitas k.m.n., Hypersensitivitas, Allergia, Hypersensitiv reakció (k.m.n.), allergiás reakció k.m.n., Hypersensitiv reakció
Czech Reakce přecitlivělosti, Alergická reakce, Alergie, Přecitlivělost NOS, HYSN, Alergie NOS, Reakce přecitlivělosti (NOS), Přecitlivělost, Alergická reakce NOS, Hypersensitivní syndrom, Alergická reakce (NOS), Hypersensitivní reakce (NOS), alergie, hypersenzitivita, přecitlivělost
Korean 상세불명의 알레르기
Hebrew alergia bilti spetzifit
Polish Uczulenie, Reakcja alergiczna, Nadwrażliwość, Odczyn alergiczny, Alergia