Immuno8 Flashcards
Hypersensitivity types
Anaphylactic and atopic hypersensitivity.
Type I
Cytotoxic (antibody mediated) hypersensitivity.
Type II
Immune complex–Antigen-Antibody hypersensitivity
Type III
Delayed (T-cell mediated) type hypersensitivity.
Type IV
Type I hypersensitivity test.
skin test for specific IgE
Type II hypersensitivity test.
Direct and Indirect Coombs’
Type III hypersensitivity test.
Immunofluorescent staining
Type IV hypersensitivity test.
Patch test, PPD (TB test)
What is the Mnemonic for hypersensitivity reactions?
“ACID”
Anaphylactic and Atopic (type I) Cytotoxic-Ab mediated (type II) Immune complex (type III) Delayed-cell mediated (type IV)
Type I hypersensitivity characteristics.
- Free antigen cross-links IgE on presensitized mast cells and basophils – Release vasoactive amines that act on postcapillary venules (i.e., histamine)
- Reaction develops Rapidly after Ag exposure because of PREFORMED antibody
Type II hypersensitivity characteristics.
-IgM, IgG bind to fixed antigen on “enemy” cell, leading to cellular destruction
What are the 3 mechanisms of Type II hypersensitivity?
1-Opsonization (phagocytosis or complement activation)
2-Complement-mediated lyssi
3-Antibody-Dependent Cell-Mediated Cytotoxicity (ADCC), usually due to NK cells
Type III hypersensitivity characteristics.
- Ag-Ab (IgG) complexes activate complement, which attracts neutrophils
- Neuts release lysosomal enzymes
What is Serum Sickness?
- Type III hypersensitivity
- Abs to foreign proteins are produced (takes 5 days)
- Immune complexes form and are deposited in membranes, where they fix complement (leads to tissue damage)
What causes Serum Sickness? What are the Symptoms?
-Drugs acting as Haptans S/S: -Fever -Urticaria -Arthralgias -Proteinuria -Lymphadenopathy