week 5 allergies, hypersensitivities, vaccines Flashcards
What is the name of the peptide that is released from mast cells and causes hypersensitivity and edema?
Bradykinin
What is another peptide that leads to production of Bradykinin?
Kallikrein
What are the effects of Bradykinin?
Edema. Released from mast cells -→ inflammation
What can inhibit Bradykinin production and how?
C1 Inhibitor - Inhibit coagulation Protein (?) and production of Kallikrein (C1-INH blocks generation of Bradykinin at 2 levels)
What are the causes of hypersensitivity?
- When the immune reactions are strong enough to induce immune pathology and are clinically manifest
- Excessive response to pathogens
- Some are initiated by environmental Ags (latex)
- Some are initiated by self Ags and cause autoimmune diseases
What are the two phases of hypersensitivity?
- Sensitization -asymptomatic, don’t know how it happens
- Elicitation - disease presentation - dont know the sensitizing Ag. modulated by memory immune response. Happens repeatedly
4 types of Hypersensitivity? what are they mediated by?
Type 1 -Immediate - Mediated by IgE (mast cells)
Type 2 - Ab mediated (IgG or IgM)
Type 3 - Immune complex (Ag-Ab complex circulating before going to tissues)
Type 4 - T cell mediated
4 main steps of type 1 hypersensitivity sensitization?
- 1st exposure to allergen
- Activation of follicular T cells (Tfh) and stimulation of IgE class switching in B cells
- Production of IgE
- Binding of IgE to FcεRI on mast cells
What are the two phases of the elicitation type 1 hypersensitivity? Clinical signs of each?
- Immediate hypersensitivity
- Rashes
- Sinus congestion
- Bronchial constriction
- Abdominal pain/Diarrhea
- Systemic shock
- Anaphylaxis
- late phase reaction
- Due to the accumulation of inflammatory leukocytes, including neutrophils, eosinophils, basophils, and TH2 cells, PGN, LTN
- May occur without a detectable immediate hypersensitivity reaction
What are the effectors of elicitation step of type 1 hypersensitivity?
Mast cells, Basophils, Eosinophils
What are the mediators of type 1 hypersensitivity?
Mast cells (or basophils): Vasodilation, Vascular leak, Broncho-constriction, Intestinal hypermotility, Inflammation, Tissue damage
For the type 1 hypersensitivity one of the effectors is Eosinophils. How do they lead to killing of parasites?
She wants us to know that eosinophils dont bind IgE, its the Granule protein who kill parasites
you are seeing while elevated roundish patches on the skin of a patent that has been given allergen markers. Explain your findings
Wheel and flare - result of type 1 immediate hypersensitivity
Wheel - patch on the skin thats elevated
Flare - erythema/redness
List the diseases of type 1 hypersensitivity?
- Systemic Anaphylaxis
- Bronchial Asthma
- Urticaria (Hives)
- Atopic Dermatitis
- Allergic rhinitis (Hay fever)
- Food allergies
Symptoms and tx of Systemic Anaphylaxis?
Type 1 hypersensitivity.
Massive release of histamine, leukotrienes, prostaglandins, & cytokines
Constriction of the airways, laryngeal edema, hives in the skin, nausea
Treatment: Epinephrine; Antihistamines; Cortisone
Symptoms and tx of Bronchial astma?
Type 1 hypersensitivity.
- Airway obstruction; Chronic bronchial inflammation with eosinophils
- Increased production of thick mucus
- Treatment: Inhaled corticosteroids (Long-term); Albuterol (Rescue inhalers)
Symptoms and tx of Urticaria (Hives)?
Type 1 hypersensitivity.
- Mediated largely by histamine
- Treatment: Avoidance of known triggers; Antihistamines
Symptoms and tx of Atopic dermatitis?
Type 1 hypersensitivity.
- Can be blocked by corticosteroids, which inhibit cytokine synthesis
- As a late-phase inflammatory reaction, it is not inhibited by antihistamines
Symptoms and tx of Allergic rhinitis (Hay fever)?
Type 1 hypersensitivity.
– Edema, irritation, mucus in nasal mucosa
- Treatment: Corticosteroids; Antihistamines; Pseudoephedrine (Decongestants)
Symptoms and tx of Food allergies?
- Hives and GI problems
- Treatment: Antihistamines; Epinephrine
Special thing about Type II Hypersensitivity Reactions?
They are not systemic. Specific to the tissues where AGs are present (AB mediated - IgG, IgM)
What are the two main mechanisms by which the pathology is caused in type 2 hypersensitivity?
- Activation of complement
- Antibody-Dependent Cellular Cytotoxicity (ADCC) - hemolytic disease of the newborn - HDNB
What are the 5 cytotoxic type 2 hypersensitivity reactions?
Transfusion Reactions
Autoimmune Hemolytic Anemia
Goodpasture syndrome
Pemphigus Vulgaris
Rheumatic Fever - Untreated GAS pharyngitis
Mechanisms of Pathogenesis of Transfusion Reactions?
Its a cytotoxic Type II Hypersensitivity Reactions
- Abs to proteins on transfused, incompatible RBCs (hemolysis)
