Type I hypersensitivity

Type I hypersensitivity

Infobox_Disease
Name = Type I hypersensitivity


Caption = SEM of miscellaneous plant pollens. Pollens are very common allergens.
DiseasesDB =
ICD10 =
ICD9 =
ICDO =
OMIM =
MedlinePlus =
eMedicineSubj =
eMedicineTopic =
MeshID = D006969

Type I hypersensitivity (or immediate hypersensitivity) is an allergic reaction provoked by reexposure to a specific type of antigen referred to as an allergen. [eMedicine|med|1101]

Exposure may be by ingestion, inhalation, injection, or direct contact.

Pathophysiology

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.cite web |url=http://student.ccbcmd.edu/courses/bio141/lecguide/unit5/hypersensitivity/type1/type1.html |title=The Adaptive Immune System: Type I Immediate Hypersensitivity |format= |work= |accessdate=2008-09-22] 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 histamine, leukotriene, and prostaglandin that act on the surrounding tissues. The principal effects of these products are vasodilation and smooth-muscle contraction.

The reaction may be either local or systemic. Symptoms vary from mild irritation to sudden death from anaphylactic shock.

Treatment and prognosis

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.

Examples

Some examples:
*Allergic asthma
*Allergic conjunctivitis
*Allergic rhinitis ("hay fever")
*Anaphylaxis
*Angioedema
*Urticaria (hives)
*Eosinophilia
*Penicillin
*Cephalosporin

References


Wikimedia Foundation. 2010.

Игры ⚽ Поможем написать реферат

Look at other dictionaries:

  • Type IV hypersensitivity — Classification and external resources MeSH D006968 Type IV hypersensitivity is often called delayed type hypersensitivity as the reaction takes two to three days to develop. Unlike the other types, it is not antibody mediated but rather is a type …   Wikipedia

  • type IV hypersensitivity — hypersensitivity initiated by antigen specific T lymphocytes; unlike forms mediated by antibodies, it takes one or more days to develop and can be transferred by lymphocytes but not by serum. The term is often equated with delayed… …   Medical dictionary

  • type I hypersensitivity — hypersensitivity that occurs rapidly (within several minutes) upon reexposure to an antigen, due to interaction of IgE and the antigen; see type I hypersensitivity reaction, under hypersensitivity reaction, at reaction …   Medical dictionary

  • type II hypersensitivity — hypersensitivity resulting from antibody antigen interactions on cell surfaces; see type II hypersensitivity reaction, under hypersensitivity reaction, at reaction. Called also antibody mediated h …   Medical dictionary

  • type III hypersensitivity — hypersensitivity due to formation of circulating antigen antibody complexes and their deposition in tissues; see type III hypersensitivity reaction, under hypersensitivity reaction, at reaction. Called also immune complex–mediated h …   Medical dictionary

  • Type III hypersensitivity — Infobox Disease Name = PAGENAME Caption = DiseasesDB = ICD10 = ICD9 = ICDO = OMIM = MedlinePlus = eMedicineSubj = eMedicineTopic = MeshID = D007105 Type III hypersensitivity occurs when antigens and antibodies are present in roughly equal amounts …   Wikipedia

  • Type II hypersensitivity — In type II hypersensitivity (or cytotoxic hypersensitivity)cite web |url=http://pathmicro.med.sc.edu/ghaffar/hyper00.htm |title=Hypersensitivity reactions |format= |work= |accessdate=] the antibodies produced by the immune response bind to… …   Wikipedia

  • type IV hypersensitivity — A delayed hypersensitivity response (it appears 24 to 48 hours after antigen exposure). It results from the binding of antigen to activated T lymphocytes, which then release cytokines and trigger inflammation and macrophage attacks that damage… …   Dictionary of microbiology

  • Type V hypersensitivity reaction — A Type V hypersensitivity reaction occurs when IgG class antibodies directed towards cell surface antigens have a stimulating effect on their target.Grave s disease is an example of this type of hypersensitivity reaction. This disease is also… …   Wikipedia

  • type I hypersensitivity — A form of immediate hypersensitivity arising from the binding of antigen to IgE attached to mast cells, which then release anaphylaxis mediators such as histamine. Examples: hay fever, asthma, and food allergies …   Dictionary of microbiology

Share the article and excerpts

Direct link
… Do a right-click on the link above
and select “Copy Link”