14 - Allergy and Hypersensitivity

Question 1

What are hypersensitivities?

Answer 1

inappropriate immune response to antigens that pose little to no threat

Question 2

Which antibodies are responsible for Type I hypersensitivities?

Answer 2

IgE antibodies

Question 3

What are allergies initiated by?

Answer 3

interaction between an IgE and a multivalent antigen

Question 4

What are the 6 common allergic reactions?

Answer 4

hay fever | asthma | eczema | bee stings | hives | food allergies

Question 5

What are atopic individuals?

Answer 5

people who are susceptible to allergens

Question 6

What is IgE only supposed to respond to?

Answer 6

pathogens specifically parasitic infections

Question 7

What are 2 properties of allergens?

Answer 7

enzymatic protease = break through barriers | PAMPS = trigger activation and immune system

Question 8

What are allergens?

Answer 8

non-parasitic antigens

Question 9

In Type I hypersensitivity reactions, how do IgE antibodies act?

Answer 9

IgE = bound to mast cells | cross-linking Fce receptors on surfaces of innate immune cells (mast cells) = degranulation

Question 10

What are in the granules of granulocytes?

Answer 10

histamine | heparin | proteases | leukotrines | prostaglandins | chemokines

Question 11

If there is no allergen present during degranulation, what will happen to the contents of the granules?

Answer 11

will impact the tissue it is near = cause inflammation

Question 12

What is the Fc receptor involved in Type I hypersensitivity?

Answer 12

FceR

Question 13

On which cells are FceR only found on?

Answer 13

mast cells | eosinophils | basophils

Question 14

What does histamine cause?

Answer 14

contraction of intestinal and bronchial smooth muscles | mucus secretion | increase vasopermeability and vasodilation | mast cell chemotaxis

Question 15

What do prostaglandins and leukotrienes cause?

Answer 15

vascular permeability | mucus secretion | major cause of asthma symptoms

Question 16

In Type I hypersensitivity, what does IL-5 do?

Answer 16

recruits and activates eosinophils

Question 17

In Type I hypersensitivity, what does TNFa do?

Answer 17

contribute to shock in systemic anaphylaxis

Question 18

What is CXCL-8?

Answer 18

chemotactic factor

Question 19

In Type I hypersensitivity, what does IL-13 do?

Answer 19

helps with mucus secretion, goblet cells, hyperplasia

Question 20

In Type I hypersensitivity, what does GM-CSF do?

Answer 20

helps with production of granulocytes

Question 21

What is the early response during a Type I hypersensitivity reaction?

Answer 21

mast cells induce vasodilation | bronchoconstriction and goblet cells produce mucus = hard to breathe

Question 22

What is the late response during a Type I hypersensitivity?

Answer 22

more cells and inflammation to surrounding tissue | chemokine and cytokine production | eosinophil recruit neutrophils and induce degranulation

Question 23

What are the 3 categories of Type I hypersensitivity reactions?

Answer 23

systemic anaphylaxis | localized hypersensitivity reactions | food allergies

Question 24

What are 2 symptoms of systemic anaphylaxis? What is the treatment?

Answer 24

drop in BP = leads to shock | smooth muscles contract = bronchoconstriction | Tx = epinephrine

Question 25

What is the basis or cause for Type I hypersensitivity?

Answer 25

environmental factors | hygiene hypothesis | genetic factors

Question 26

What is the main idea of the hygiene hypothesis?

Answer 26

using Th2 cells at a younger age would help the body balance the Th1 response with Th2

Question 27

How can genetics cause Type I hypersensitivity?

Answer 27

increased IgE production and more of a Th2 response

Question 28

Which Th subsets counteract Th2 responses?

Answer 28

Treg and Th1

Question 29

What are the 2 diagnostic methods used for Type I hypersensitivity reactions?

Answer 29

skin test | allergen-specific IgE levels in serum

Question 30

What are 2 treatments for Type I hypersensitivity?

Answer 30

antagonists for the granule contents (anti-histamines, etc) | desensitization immunotherapy

Question 31

What is desensitization immunotherapy?

Answer 31

induce Th1 and Treg responses

Question 32

What is Type II sensitivity involved with?

Answer 32

complement activation (mostly) | ADCC = antibody-dependent cell cytotoxicity and NK cell-mediated

Question 33

What causes Type II sensitivity reactions?

Answer 33

blood incompatibilities such as transfusion reactions, autoimmune hemolytic anemia, HDN

Question 34

What are blood group antigens made out of?

Answer 34

carbohydrates

Question 35

How are antibodies involved with blood typing and how can this result in a Type II hypersensitivity reaction?

Answer 35

adults have antibodies against the blood group antigen they DON'T have

Question 36

Which is the universal blood group donor?

Answer 36

O

Question 37

Which is the universal blood group acceptor?

Answer 37

AB

Question 38

What is the hemolytic disease of a newborn (HDN)?

Answer 38

when mom is Rh- but baby is Rh+ = mom's Abs will attack baby's Rh+ RBCs | 2nd pregnancy = kills fetus

Question 39

What is the treatment for HDN?

Answer 39

UV lights = breaks down bilirubin

Question 40

What is a preventive measure for HDN?

Answer 40

rhogam shot = IgG abs against Rh-factor

Question 41

What is responsible for Type III hypersensitivity?

Answer 41

immune complexes = Ag/Ab complexes | complexes usually get cleared after a while if no autoimmune disease or drug inducing it to stay

Question 42

What does Type III hypersensitivity cause?

Answer 42

complement activation = inflammation and recruitment of neutrophils

Question 43

What are 3 key symptoms of Type III hypersensitivity?

Answer 43

joint pain due to complex deposits | proteinuria (protein in urine) | hematuria (blood in urine) due to complexes stuck on kidneys

Question 44

What can induce Type III hypersensitivity reactions?

Answer 44

autoimmune diseases | drug reactions | infectious diseases

Question 45

What is responsible for Type IV hypersensitivity reactions?

Answer 45

cell-mediated, initiated by T-cells, Th1 cells involved

Question 46

What is Type IV sensitivity also called?

Answer 46

delayed type hypersensitivity = needs time for the reaction to develop about 1-2 weeks

Question 47

What is Type IV hypersensitivity characterized by?

Answer 47

recruitment of macrophages at the inflammation site

Question 48

What is the most common example of Type IV hypersensitivity?

Answer 48

poison ivy contact dermatitis

Question 49

Why are macrophages important for Type IV hypersensitivity reactions?

Answer 49

macrophages = responsible for the inflammation

Question 50

What is the early phase of Type IV hypersensitivity reactions?

Answer 50

sensitization phase = initiation of reaction involves sensitization by antigen = trigger T-cell (Th) response

Question 51

What is the late phase of Type IV hypersensitivity reactions?

Answer 51

second exposure of antigen = induction of Th1 inflammatory cytokines = activate macrophages = granuloma formation