Hypersenns III,IV
-
Upload
yulistio-ervano -
Category
Documents
-
view
234 -
download
0
Transcript of Hypersenns III,IV
-
7/29/2019 Hypersenns III,IV
1/15
-
7/29/2019 Hypersenns III,IV
2/15
Type III Hypersensitivity
Immune Complex Mediated Reaction
-
7/29/2019 Hypersenns III,IV
3/15
Type III: Immune Complex Mediated Reaction
*When antibodies (Ig G or Ig M) and antigen coexistimmune complexes are formed
*Immune complexes are removed by reticuloendoth. syst.
*Some immune complexesescape phagocytosis
*Immune complexes deposited in tissues on the basementmembrane of blood vessels and cause tissue injury
-
7/29/2019 Hypersenns III,IV
4/15
Mechanism Of Tissue Injury
Immune complexes trigger inflammatory processes:
activate release
1) Immune complexes the complement anaphylatoxins C3a, C5a
stimulate release
degranulation of basophiles and mast cells histamine
Histamine vascular permeability and help deposition of immune complexes
2) Neutrophils are attracted to the site by immune complexes and releaselysosomal enzymes which damage tissues and intensify the inflammat. Pro.
3) Platelets are aggregated with two consequences
a- release of histamine
b- form of microthrombi which lead to ischemia
-
7/29/2019 Hypersenns III,IV
5/15
Clinical conditions of Type III Hypersensitivity
Diseases produced by immune complexes are those inwhich antigens persists without being eliminated as:
a- Repeated exposure to extrinsic antigen
b- injection of large amounts of antigens
c- Persistent infections
d- Autoimmunity to self components
-
7/29/2019 Hypersenns III,IV
6/15
1- Arthus Reaction
* This is a local immune complex deposition phenomenon
e.g. diabetic patients receiving insulin subcutaneously
edema
* Local reactions in the form of erythema
necrosis
deposited
* Immune complexes in small blood vessels
vasculitis
leading to microthrombi formation
vascular occlusion
necrosis
-
7/29/2019 Hypersenns III,IV
7/15
2- Serum Sickness* A systemic immune complex phenomenon
* Injection of large doses of foreign serum* Antigen is slowly cleared from circulation
* Immune complexes are deposited in various sites
feverurticaria
* 10 days after injection arthralgia
lymphadenopathy
splenomegalyglomerulonephritis
antidiphtheritic serum
e.g. treatment with penicillinsul honamides
-
7/29/2019 Hypersenns III,IV
8/15
Type III Hypersensitivity Clinical Conditions
3- Post-streptococcal glomerulonephritis
glomerulitis associated with infective endocarditis
4- Hypersensitive pneumonitis (farmer lung)immune complexes depositition in lung after repeatedinhalation of dust , mould spores
5- Endogenous antigen antibody complexes involved inautoimmune diseases
e.g. SLE, rheumatoid arthritis
-
7/29/2019 Hypersenns III,IV
9/15
Type IV
Cell MediatedDelayed Type Hypersensitivity
-
7/29/2019 Hypersenns III,IV
10/15
Type IV: Cell Mediated
Delayed Type Hypersensitivity
triggering DTH reactions by TH1
* T-cells cause tissue injury by or
directly killing target cells by CD8
* TH1 and CD8 T cells secrete cytokines (IFN- and TNF)
attract lymphocytes
* Cytokines activate macrophages
induce inflammation
* Tissue damage results from products of activated macrophages
-
7/29/2019 Hypersenns III,IV
11/15
Tuberculin Type Hypersensitivity
* When PPD is injected intradermally in sensitized person
* Local indurated area appears injection site (48-72 hs)
* Indurations due to accumulation Of:
macrophages and lymphocytes
* Similar reactions observed in diseases
e.g. brucellosis, lepromin test in leprosy, Freis test in
lymphogranuloma venereum
-
7/29/2019 Hypersenns III,IV
12/15
Granulomatous lesions
* In chronic diseases : T.B., Leprosy, schistosomiases
* Intracellular organisms resist destruction by macrophag.
* Persistent antigen in tissues stimulate local DTH reaction
* Continuous release of cytokines leads to accumulation o
macrophages which give rise to epitheloidal and giantcell granuloma
-
7/29/2019 Hypersenns III,IV
13/15
Contact Dermatitis
* Contact of skin with chemical substances or drugs
e.g. poison, hair dyes, cosmetics, soaps, neomycin
* These substances enter skin in small molecules
* They are haptens that attached to body proteins, formimmunogenic substances
* DTH reaction to these immunogenic subst. lead to:
eczyma
inflammtory reaction of skin in rash
vesicular eruption
-
7/29/2019 Hypersenns III,IV
14/15
Type IV Hypersensitivity Clinical Conditions
4) Autoimmune diseases and graft rejection are due toin part to delayed hypersensitivity reactions
5) Insulin dependant diabetes mellitus
T-cells invade the pancreatic islets and specificallydestroy insulin secreting beta cells
-
7/29/2019 Hypersenns III,IV
15/15
Thanks