Allergies

Question 1

Type of Hypersensitivity Reaction Allergies Are

Answer 1

Type I (Immediate) Hypersensitivity, mediated mainly by Th2 but also IgE

Question 2

4 Effector Functions of Th2s (in relation here)

Answer 2

Promote IgE, Ephil, and mast cell mediated immune rxns

Protect against helminthic infections

Question 3

IgE Mediated Response Step 1

Answer 3

Sensitization - exposure to Ag and activation of Th2 to release IL-4 and IL-13, stimulating Bc CS and IgE production. IgEs circulate through peripherals to find mast cells

Question 4

FcepsilonR1

Answer 4

IgE binding R on mast cells and basophils

Has very high affinity so mast cells get coated w/ IgEs and are ready to be activated

Question 5

2 Kinds of Mast Cells (location, granule contents) & 1 major point

Answer 5

Mucosal - in alveoli/intestinal mucosa, releases leukotrienes
Connective Tissue - skin/intestinal submucosa, histamine and other shit
Populations are not fixed and can change depending on cytokine environment

Question 6

IgE Mediated Response Step 2

Answer 6

Clinical Allergy - re-exposure of Ag binds to IgE and causes crosslinking, causing mast cell activation

Question 7

2 Phases of Mast Cell Activation

Answer 7

Immediate Phase - degranulate vasoactive amines and synth/sec lipid mediators
Late Phase - synth/sec cytokines

Question 8

Actions of Vasoactive Amines and Lipid Mediators

Answer 8

Main vasodilation, vascular leak, and intestinal motility, but lipid mediators also recruit inflammatory cells

Question 9

3 Important Lipid Mediators

Answer 9

Prostaglandin D2
Leukotrienes
Platelet-activating factor

Question 10

5 Important Late-Phase Cytokines and Actions

Answer 10

TNF-alpha: inflam recruitment and bronchial response
IL-3: mast cell prolif
IL-4 and 13: IgE prolif and mucous secretion
IL-5: ephil activation

Question 11

Basophil Key Difference from Mast Cells

Answer 11

Circulate in blood rather than in peripheral tissues

Question 12

Eosinophil 6 Notable Features (location, contents/secretions, activation, involvements)

Answer 12

Abundant in late phase reactions
Line peripheral tissue linings
Activated by IL-5 but NOT IgE (R lacks beta chain, not sure why it’s there)
Heavily involved with asthma
Granulytic contents highly destructive to helminths, bacteria, and own tissues
Leukotrienes and cytokines help ephil activation/growth

Question 13

Theory of Increasing Atopic Diseases

Answer 13

Hygiene Hypothesis - activation of innate IS by microbes shifts towards Th1 response but now we’re not getting that, so Th2 is overstimulated

Question 14

2.2 Kinds of Allergy Diagnosis

Answer 14

Skin prick (preferred)
Serumspecific IgE testing (RAST and ImmunoCap)

Question 15

Immunotherapy

Answer 15

Subcut injections of dilute allergen, slowly increased over months and continued for 3-5 years

Question 16

System Anaphylaxis

Answer 16

Activated mast cells/anaphylactic response in 2+ organ systems

Question 17

2 Kinds of Non IgE Anaphylaxis

Answer 17

Complement bypasses IgE (C3-5a)
Radiocontrast Media (NOT cross reactive with anything else like shellfish)