関: hypersensitivity reactions＆type I

WordNet

of the present time and place; "the immediate revisions"
performed with little or no delay; "an immediate reply to my letter"; "a prompt reply"; "was quick to respond"; "a straightaway denial" (同)prompt, quick, straightaway
having no intervening medium; "an immediate influence"
immediately before or after as in a chain of cause and effect; "the immediate result"; "the immediate cause of the trouble"
pathological sensitivity
extreme sensitivity

PrepTutorEJDIC

『即座の』,即時の / 当座の,当面の / (時間・空間的に)すぐ近くの / 直接の,じかの(direct)
過敏,過敏症

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/06/02 21:14:53」(JST)

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Type I hypersensitivity (or immediate hypersensitivity) is an allergic reaction provoked by reexposure to a specific type of antigen referred to as an allergen.^[1] Type I is not to be confused with Type II, Type III, or Type IV hypersensitivities.

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

Pathophysiology

In type 1 hypersensitivity, an antigen is presented to CD4+ Th2 cells specific to the antigen that stimulate B-cell production of IgE antibodies also specific to the antigen. The difference between a normal infectious immune response and a type 1 hypersensitivity response is that in type 1 hypersensitivity the antibody is IgE instead of IgA, IgG, or IgM. During sensitisation, the IgE antibodies bind to Fcε receptors on the surface of tissue mast cells and blood basophils.^[2] Mast cells and basophils coated by IgE antibodies are "sensitised." Later exposure to the same allergen cross-links the bound IgE on sensitised cells, resulting in degranulation and the secretion of pharmacologically active mediators such as histamine, leukotriene (LTC4 and LTD4), and prostaglandin that act on the surrounding tissues. The principal effects of these products are vasodilation and smooth-muscle contraction.

Type 1 hypersensitivity can be further classified into an immediate and late-phase reaction. The immediate hypersensitivity reaction occurs minutes after exposure and includes release of vasoactive amines and lipid mediators, whereas the late-phase reaction occurs 2–4 hours after exposure and includes the release of cytokines.^[3]

Overview of mediators released by mast cells in type 1 hypersensitivity, and their actions:
Vasodilation and increased permeability	Histamine PAF Leukotriene C4, D4 and E4 Prostaglandin D2 Neutral proteases
Smooth muscle spasm	Histamine PAF Leukotriene C4, D4 and E4 Prostaglandin
Leukocyte extravasation	Cytokines (e.g. chemokines and TNF) Leukotriene B4 Chemotactic factors for neutrophils and eosinophils
Unless otherwise specified, the reference for this table is:^[4]

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 adrenaline (epinephrine), antihistamines, and corticosteroids. If the entire body gets involved, then anaphylaxis can take place, which is 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 allergy
Cephalosporin allergy
Food allergy

References

^ med/1101 at eMedicine
^ "The Adaptive Immune System: Type I Immediate Hypersensitivity". Retrieved 2008-09-22.
^ Shiv Pillai MD; Abul K. Abbas MBBS; Andrew Wilson PhD (2011). Cellular and Molecular Immunology: with STUDENT CONSULT Online Access. Philadelphia: Saunders. ISBN 1-4377-1528-1.
^ Table 5-2 in:Mitchell, Richard Sheppard; Kumar, Vinay; Abbas, Abul K.; Fausto, Nelson. Robbins Basic Pathology. Philadelphia: Saunders. ISBN 1-4160-2973-7. 8th edition.

External links

Type I hypersensitivity (Flash Animation)

UpToDate Contents

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English Journal

Effect of premedications in a murine model of asparaginase hypersensitivity.

Fernandez CA1, Smith C1, Karol SE1, Ramsey LB1, Liu C1, Pui CH1, Jeha S1, Evans WE1, Finkelman FD1, Relling MV2.
The Journal of pharmacology and experimental therapeutics.J Pharmacol Exp Ther.2015 Mar;352(3):541-51. doi: 10.1124/jpet.114.220780. Epub 2015 Jan 8.
A murine model was developed that recapitulates key features of clinical hypersensitivity to Escherichia coli asparaginase. Sensitized mice developed high levels of anti-asparaginase IgG antibodies and had immediate hypersensitivity reactions to asparaginase upon challenge. Sensitized mice had compl
PMID 25573198

Nano/micro fluorhydroxyapatite crystal pastes in the treatment of dentin hypersensitivity: an in vitro study.

Taha ST1, Han H, Chang SR, Sovadinova I, Kuroda K, Langford RM, Clarkson BH.
Clinical oral investigations.Clin Oral Investig.2015 Feb 14. [Epub ahead of print]
OBJECTIVES: Dentin hypersensitivity (DH) is a prevalent problem. This study aimed to formulate a paste using fluorhydroxyapatite (FA) crystals dispersed in different carriers to treat DH. The ability to occlude patent dentinal tubules and to release ions was investigated.MATERIALS AND METHODS: Twent
PMID 25680707

Anaphylactic reactions to low-molecular weight chemicals.

Nowak D1, Panaszek B1.
Postȩpy higieny i medycyny doświadczalnej (Online).Postepy Hig Med Dosw (Online).2015 Feb 6;69(0):197-206.
Low-molecular weight chemicals (haptens) include a large group of chemical compounds occurring in work environment, items of everyday use (cleaning products, clothing, footwear, gloves, furniture), jewelry (earrings, bracelets), drugs, especially in cosmetics. They cause type IV hypersensitive react
PMID 25661919