31 ĐỀ THI THỬ VÀO LỚP 10 - TIẾNG ANH - FORM MỚI 2025 - 40 CÂU HỎI - BÙI VĂN V...
Hypersensitivity type -3 reactions
1.
2. Immune Complex-Mediated (Type III)
Hypersensitivity:
Antigen combines with antibody within the
circulation (circulating immune complexes) , and
these are deposited.
Antigen-antibody complexes produce tissue damage
by eliciting inflammation at sites of deposition.
Two types of antigens cause immune complex-
mediated injury:
(1) exogenous antigens: such as foreign protein,
bacterium, or virus.(microbial proteins)
(2) endogenous antigens: individual can produce
antibody against self-components such as
nucleoproteins.
3. IMMUNE COMPLEXES
Antigen binds to IgG and
forms complex and
circulate through the blood
Larger complexes activate
complement in the blood
and are phagocytosed by
macrophages.
These moderate complexes
are deposited in the
basement membranes of
blood vessels and tissues.
Here they cause
inflammation of target
tissue/organ through the
attraction of leucocytes
leading to anaphylactic
shock.
4.
5. 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 release
lysosomal enzymes which damage tissues and intensify the inflammation process.
8. Immune complex-mediated diseases can be:
generalized (systemic) ; or localized .
Systemic Immune Complex Disease:
Acute serum sickness: Once complexes are
deposited in tissues, they initiate an acute
inflammatory reaction (approximately 10 days after
antigen administration), clinical features such as
fever, urticaria, arthralgias, lymph node enlargement,
and proteinuria appear.
Local Immune Complex Disease :
Arthus reaction: a localized area of tissue
necrosis resulting from acute immune complex
vasculitis, usually elicited in skin.
9.
10.
11.
12. ARTHUS REACTION
Local inflammatory reaction with Necrosis
Few hours after Ag inoculation
Inoculated Animal is previously immunized by same Ag
immunized animal has titers of precipitating IgG Abs
Arthus lesions evolve over a few hours and reach a
peak 4 to 10 hrs after injection
When injection site develops visible edema with severe
hemorrhage occasionally followed by ulceration