Hypersensitivity reactions and Asthma Flashcards
1
Q
Hypersensitivity reactions
A
- Immune reactions that lead to tissue injury.
- may be antibody or T cell mediated
- may lead to autoimmune diseases.
- classified based on the principal immunological mechanism that is responsible for tissue injury.
2
Q
Immediate hypersensitivity (Type 1 )
A
- against environmental antigens (allergens)
- mediated via IgE which then binds to FcɛRI on the surface of mast cells.
- Upon second exposure to the antigen, mast cells degranulate leading to rapid vasodilation and inflammation at the site of exposure
- hay fever, food allergies, bronchial asthma, skin allergies, and anaphylaxis if systemic.
3
Q
atopic
A
Individuals who are prone to develop allergic diseases
4
Q
Omalizumab
A
- Anti-IgE antibody
- neutralize and eliminate IgE
5
Q
Syndrome : Anaphylaxis
A
- Therapy : Epinephrine
- MOA : Vascular smooth muscle contration; increases cardiac output to counter shock; inhibits further mast cell degranulation.
6
Q
Bronchial-Asthma
A
Therapy & MOA
- COC-steroids ( reduce inflammation)
- Leukotriene anta ( reduce inflammation)
- Phosphodiesterase inhibitors ( relax bronchial smooth muscles)
7
Q
Antihistamines
A
block actions of histamine on vessels and smooth muscles
8
Q
Cromolyn
A
inhibits mast cell degranulation
9
Q
Type II
A
- IgG-mediated cytotoxic Hypersensitivity
- Antibody directed against cell surface antigens mediates cell destruction via complement activation
- Ex: Acute rheumatic fever; Blood transfuion reactions, erthroblastosis fetalis, autoimmune hemolytic anemia; Myasthenia Gravis; Graves’ Disease (hyperthyroidism); pernicious anemia
10
Q
Type III
A
- Immune complex-mediated
- Antigen-Antibody complexes deposited in various tissues induce complement activation and resulting in inglammatory response mediated by massive infiltration of neutrophils
- RA; Lupus; poststreptococcal glomerulonephiritis
11
Q
therapies for Type II and III
A
- IVIG (intravenous IgG from healthy donors) - may block Fc recetors on phagocytes so pathogenic antibodies do not bind
- Antibodies specific to CD20 on B cells result in their depletion or antibodies that block CD40 OR CD40L can inhibit B cell activation.
12
Q
T cell mediated diseases (Type IV or delayed hypersensitivity reactions )
A
- the result of autoimmunity or due to persistent responses to environmental antigens
- against cellular antigens with restricted tissue distribution and thus reactions are localized and not systemic
- Th1, Th17 or CTLs
- Sensitized Th1 ce;;s re;ease cytokines that activate macrophages of Tc cells which mediate direct cell damage
- Ex: Contact dermatitis, TB lesions and graft rejection.
13
Q
Treatments of Type IV hypersensitivity:
A
- Steroids
- Anti-TNFs in RA or IBD
- Drugs that block B7 molecules
- IL-1, IL-6, or IL-17 antagonists
14
Q
Granulomatous hypersensitivity
A
- occurs as a defense against intracellular infections such as T.B.
- macrophages + other immune cells form a core of inflammatory cells that include lymphocytes, eosinophils, plasma cells, giant cells, and epithelioid cells to localize the infection.
- These collections of cells develop into a ball-like mass called granuloma.
15
Q
Mechanisms by which autoantibodies cause disease
A
- Inflammation
- Opsonization and Phagocytosis
- Abnormal cellular responses
