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Hypersensivity Reactions and Damage caused by the İmmun System - Coggle…
Hypersensivity Reactions and Damage caused by the İmmun System
What are the major types of hypersensitivity
reactions?
T Cell-mediated (Type 4)
İmmune Complex-mediated (Type 3)
Antibody-mediated (Type 2)
İmmediate Hypersensivity (Type 1)
tanım
Injurious, or
pathologic, immune reactions are called hypersensitivity reactions.
Başlıca 2 sebeple görürüz bunlar
1) responses to foreign antigens (microbes and noninfectious environmental antigens) may cause tissue injury,
2) the immune responses may be
directed against self (autologous) antigens, as a
result of the failure of self-tolerance
İmmediate Hypersensitive (Type 1)
tanımı ve özellikleri
Bunun hastalıklarına
Allergy
ya da
Atopy
denir. Hastasına ise
Atopic
denir
example: Hay fever, Food allergy, Bronchial asthma, anaphylaxis
is an
IgE antibody– and mast cell
–mediated reaction to certain antigens that causes rapid vascular leakage and mucosal secretions, often followed by inflammation.
Mechanism
1) Activation Th2 and İL-4 secreting follicular Helper T (Tfh) cell
2) they stimulate production İgE antibodies
3) Binding of İgE to specific Fc receptors of mast cell
4) then on subsequent exposure to the
antigen
5) cross-linking of the bound IgE by
the antigen, and release of mast cell mediators
Mast cell üzerindeki İgE lerin antijenlere bağlanmasıyla aktive olarak başlıca 3 şekilde tepki verir bunlar
a) rapid release of granule contents b) synthesis and secretion of lipid mediators c)synthesis and secretion of cytokines
.
The most importan mediators
newly generated and secreted products of
arachidonic acid metabolism,
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cytokines
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vasoactive amines
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proteases stored in and released from granules,
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Allerjen için üretilen İgE lerin mast hücrelerdeki Fc receptörlerine yüksek affinitesi vardır. Zaten bu sayede mast hücreleri İgE kaplıdır. Atopik kişilerde ise antigene özgü İgE ile daha çok kaplıdır. Normal bireyler bir çok antigene özgü İgE Bulunduğu için üretilen mediatörler İmmediate Hypersensitive neden olmayacak kadar azdır. İgE ye yüksek affinitesi olan receptörün adı
FcεRI
dır. 3 polipeptit zinciri içerir. bunlardanbiri
Fc nin heavy chain kısmına yüksek oranda bağlana kısım
iken diğer ikisi
signaling proteinlerdir
nedeni çok anlaşılamayan bir şekilde bazı bireyler protein ya da proteşnlere bağlanan kimyasallara karşı hassasiyet gösterir. bu antigenlere
Allergen
denir. Th2 or Tfh dan salgılanan 2 sitokin (İL-4 ve İL-13) B lymphositlerini İgE dönüşmesi için uyarır.(Atopik kişilerde) İmmadiate hypersensitive güçlü bir gentik tmele sahiptir bir çok farklı gen buna katkı sağlar ama çok anlaşılamamıştır
Clinical Syndrome and Threapy
örnekleri
Food allergies
İncreased peristealysis due to conration of intestinal muscles
Bronchial asthma
Airway obstruction caused by bronchial smooth muscle hyperactivite inflammation and tissue injury caused by late-phase reaction
Leukotriene antagonists
Relax bronchial smooth
muscle and reduce inflammation
Phosphodiesterase
inhibitors
Relax bronchial
smooth muscles
corticosteroid
Reduce inflammation
Allergic rhinitis. sinusitis(hay fever)
İncresed mucus secretion, inflammation of upper airway, sinuses
Anaphlaxis
fall in blood pressure caused by vessel dilation airway obstructiondue to bronchoconstriction and laryngial edema
Epinephrine
causes vascular smooth muscle cell contruction, increase cardiac output and inhibits brochial smooth muscle cell contruction
Disease caused by Ab's and Ab-Ac complexes
type's
Type 2(Antibody-Mediated)
kısaca tanım
Vücudun kendi hücre ve dokularını antijen olarak görmesiyle olur.
genelde aotuantibadyler ve daha az olasılıkla yabancı antijene neden olan antibadilerle olurlar
Autoantibodies may bind to self
antigens in tissues
Type 3(İmmun complex-mediated)
kısaca tanım
Antibody kan damarlarında immun complex oluşturarak birikmesiyle
Kan akımının çok güçlü olduğu yerlerde bile birikebildiğinden
sistemik
olmaya yatkındırlar
vasculit, arthritis and nephritis.
may form immune complexes with circulating self antigens.
mechanism Tissue İnjury and Disease
Opsonization and phagocytosis
If antibodies bind
to cells, such as erythrocytes and platelets, the cells are opsonized and may be ingested and
destroyed by host phagocytes.
abnormal cellular response
s. Some antibodies may
cause disease without directly inducing tissue injury
antibodies against hormone receptors may inhibit receptor function
may directly activate receptors, mimicking their physiologic ligands.
İnflammation
Clinical Syndrome and threapy
Disase caused by T Lymphocytes
başlıca nedenleri
autoimmunity
exaggerated or persistent responses to environmental antigens.
özellikleri
directed against cellular antigens with
restricted tissue distribution
T cell–
mediated autoimmune diseases tend to be limited to a few organs and usually are not systemic
mechanism
r by killing of host cells by CD8+
CTLs
by inflammation induced
by cytokines that are produced mainly by CD4+ T cells
activation of
Th1 and Th17 cells. Th1 cells are the source of interferon-γ (IFN-γ), the principal macrophageactivating cytokine, and Th17 cells are respon sible for the recruitment of leukocytes, including
neutrophils
göstegeleri
d by infiltrates of T cells and blood
monocytes in the tissues
, edema and fibrin deposition caused by increased vascular permeability