Lecture: Hypersensitivity Flashcards
Exaggerated response to a harmless antigen that results to an injury in the tissue, disease, or even death.
Hypersensitivity
Immune System Involved in Type I Hypersensitivity
Humoral (IgE)
Type I Hypersensitivity has an onset within seconds, gaining its name “”?
Immediate Hypersensitivity
The only type of hypersensitivity that is cell-mediated is?
Type IV
Non-parasite antigens that can stimulate a type I hypersensitivity response; bind to IgE and trigger degranulation of chemical mediators
Allergens
Molecular weight of allergens
15,000 to 40,000 MW
Enzyme allergen from the fecal pellets of the dust mite
Der P1
Cytokines involved in differentiation of B cells
IL-4 and IL-13
Cytokines involved in development of eosinophils
IL-5 and IL-9
Cytokines involved in development of mast cells
IL-4 and IL-9
Cytokines involved in stimulating overproduction of mucus
IL-4, 9, 7, 13
Term for the genetic trait to have a predisposition for localized anaphylaxis
Atopy
Atopic individuals have higher levels of IgE and eosinophils. True or False?
True
High affinity IgE receptor found on mast cells/basophils/activated eosinophils
Fc ε receptors (Fc ε RI)
IgE can attach to Mast cells or basophils by Fc receptor, which increases the life span of the IgE, this process is called?
Sensitization
Secondary exposure to allergen; allergen binds IgE and cross-links to activate signal with tyrosine phosphorylation, Ca++ influx, degranulation and release of mediators
Effector Stage of Hypersensitivity
Mediator responsible for constriction of smooth muscles
Histamine
Bronchiole constriction can cause?
Wheezing
Constriction of intestine can cause?
Cramps/diarrhea
Mediators formed after activation
Secondary Mediators
Pre-formed mediators in granules
Primary Mediators
Most severe type of allergy, acute reaction that involves multiple
organs.
Anaphylaxis
Cytokines as Primary Mediators
TNF-α, IL-1, IL-6
Chemoattractants for Neutrophils and Eosinophils
NCF-A, ECF-A
Th2 cytokines as Secondary Mediators
IL-4, IL-5, IL-13, GM-CSF
Serum from Kustner who was allergic to fish was injected to Prausnitz
Passive Cutaneous Anaphylaxis
Target organ responds to direct contact with allergen
Localized Anaphylaxis
Systemic vasodilation and smooth muscle contraction leading to
severe bronchiole constriction, edema, and shock
Systemic Anaphylaxis
Repeated injections of allergen to reduce the IgE on Mast cells and produce IgG
Immunotherapy / Desensitization
Block histamine receptors
Antihistamines
In Vivo Tests
Direct Skin Testing
Cutaneous and Intradermal
Inject a drop of allergen into the skin, after 15 minutes, check
for wheal that is 3 mm higher than the control
Cutaneous/Prick Test
More concentration of allergen is used; wheal that is 3 mm higher than the control
Intradermal
Measures total IgE
Radioimmunosorbent Test
Measures allergen-specific IgE
Radioallergosorbent Test
Allows multiple allergens diagnosis with a low sample volume
Microarray Test
Type II Hypersensitivity is also known as?
Antibody-mediated cytotoxicity
Ab reacts with basement membrane protein → C’ activation → Inflammation → deposition of IgG
Goodpasture’s syndrome
Uses polyspecific AHG (Abs to IgG and C3b and C3d) – monospecific AHG
Direct Antiglobulin Test
Antigen-antibody immune complexes is involved with what type of hypersensitivity?
Type III Hypersensitivity
Serum sickness is usually a permanent immune complex disease with removal of antigen source. True or False?
False, it is transient
If neutrophils and macrophages are unable to phagocytize the
immune complexes these cells will degranulate in the area of
immune complex deposition and trigger inflammation. They are called as?
Frustrated Phagocytes
Immune complex or frustrated phagocytes deposited in joints causing local inflammation is known as?
Arthritis
Immune complex or frustrated phagocytes deposited in kidneys
Glomerulonephritis
Delayed Type Hypersensitivity is known as?
Type IV Hypersensitivity
Memory Th1 cells against DTH antigens are generated by dendritic cells during the _?
Sensitization stage
Th1 memory cells are activated and produce
cytokines: _, _ and _ which cause tissue destruction, inflammation
IFN-γ, TNF-α, and TNF-β
Th1 memory cells are activated and produce
cytokines: _ that activates CTLs
IL-2
Th1 memory cells are activated and produce
cytokines: _ for macrophage recruitment
Chemokines
Th1 memory cells are activated and produce
cytokines: _ for increased monocyte/macrophage
IL-3, GM-CSF
The response to poison oak, poison ivy, poison sumac, is a
classic Type IV
Contact Dermatitis
Allergic disease of the lung parenchyma; AKA Farmer’s lung, Pigeon Breeder’s disease, Humidifier Lung Disease
Hypersensitivity Pneumonitis
Soluble Ag from Mtb induce a reaction in people who have/have had tuberculosis
Tuberculin-Type Hypersensitivity
Purified filtrate from cell wall of Mtb
Tuberculin Skin Test/PPD
Gold standard in testing contact dermatitis
Patch Test
0.1 Ag is injected intradermally using a syringe. Test is read at 48 and 72 hours for the presence of induration
Mantoux Method
Enzymes as Primary Mediators
Tryptase, chymase, cathepsin
Anaphylaxis was coined by _ and _ meaning “”?
Portier and Ritchet
Without protection
