Hipersensitivity Reactions Flashcards
(30 cards)
Anaphylactic type reaction is characteristic of
Type I HS
Type I HS has 2 phases:
Inmediate (minutes)
Late (12-24 hours)
Type I HS is mainly mediated by
Formation of IgE Antibodies
Type I HS clinical features
Edema + Urticaria + Broncoconstriction + Rhinitis
In the first exposure: Once APCs present antigen to T-Helper cells, what is the next step in Type I HS
1) Activation of Th2 Cells = Increase of IL-4
2) Increased IL-4 = B-Cell class switching to IgE
IgE binds to Fc-epsilon receptor on
Mast cells and Basophils
2nd exposure in Type I HS
IgE antibodies crosslink = DEGRANULATION of Basophils and Mast cells
Examples of Type I HS
ASTHMA
RHINITIS
HIVES
Type II HS is mediated by
ANTIBODIES
Type II is characterized by presence of _____________ against _____________
IgG Antibodies / Cell surface Antigen
Antibodies lead to cellular damage via 3 mechanism
1) COMPLEMENT ACTIVATION
2) OPSONIZATION
3) ABNORMAL CELLULAR RESPONSES
The mechanism of abnormal cellular response in Type II HS is feature of
Myasthenia Gravis
Examples of Type II HS
Autoinmune Hemolytic Anemia
Graves Diseases
Rheumatic fever
Myasthenia Gravis
GoodPasteur Syndrome
Type III HS is mediated by
INMUNE COMPLEX
Mechanism of Type III HS
Deposition of Inmune Complexes (Antigen-Antibody) in tissues that leads to complement activation
Vasculitides are an example of
Type III HS
Examples of Type III HS
LES
PS Glomerulonephritis
Serum sickness (Passive Immunity)
Arthus Reaction (DT vaccine)
Type IV HS is mediated by
T-Cell-Mediated / Also known as Delayed Type
Abnormal activation of T-Cells is feature of
Type IV HS
CD4+ acts via ________ and produce ___________
MHC II / Harmful Cytokines
CD8+ acts via _________ and produce ___________
MHC I/ Direct Cytotoxicity
Examples of Type IV HS
Contact Dermatitis
Graft vs Host disease
Dm Type I
Tuberculin reaction
LES is an example of
Type III HS
DM Type I is an example of
Type IV HS
