Immunopathology Type 1, Allergies

Question 1

Discuss the roles of IgG in helminth immunity.

Answer 1

The IgG binds the worm and activates complement (no effect on worm) causing neutrophils to be attracted; however neutrophils have no effect on worms.

Question 2

Discuss the roles of IgE in helminth immunity.

Answer 2

IgE stuck to mast cells picks up antigens shed by the worms. The antigens cross link the IgE activating the mast cells to degranulate. The histamine that is released causes smooth muscle contractions that can drive the worm out by violent peristalsis

Question 3

Discuss the roles of M2 macrophages in helminth immunity.

Answer 3

While eosinophils are doing their job, Tfh is stimulating the B cells in the lymph nodes to switch to IgE production and Th2 goes out in the body to attract eosinophils and macrophages. The suite of lymphokines a Th2 makes (IL-4, IL-5, IL-13) turn macrophages into alternatively activated M2 macrophages which heal damage and wall off M1-resistant invaders

Question 4

Discuss the roles of eosinophils in helminth immunity.

Answer 4

Eosinophils see the IgG opsonizing the surface of the worm and bind the IgG via their Fc receptors. In doing so they release Major Basic Protein which is highly toxic to helminthes.

Question 5

Give an overview of helminth immunity

Answer 5

A person with a helminth (worm) infection will produce boatloads of IgG and IgE. The IgG binds the worm and activates complement (no effect on worm) causing neutrophils to be attracted; however neutrophils have no effect on worms. But, DON’T WORRY IgE will save the day!
IgE stuck to mast cells picks up antigens shed by the worms. The antigens cross link the IgE activating the mast cells to degranulate. The histamine that is released causes smooth muscle contractions that can drive the worm out by violent peristalsis. However, the fun comes in when the late phase reaction is activated and all parts of the ECF-A (prostaglandins and leukotrienes) send an invitation for eosinophils to come join the party. Eosinophils see the IgG opsonizing the surface of the worm and bind the IgG via their Fc receptors. In doing so they release Major Basic Protein which is highly toxic to helminthes. Meanwhile Tfh is stimulating the B cells in the lymph nodes to switch to IgE production and Th2 goes out in the body to attract eosinophils and macrophages. The suite of lymphokines a Th2 makes (IL-4, IL-5, IL-13) turn macrophages into alternatively activated M2 macrophages which heal damage and wall off M1-resistant invaders.

Question 6

atopic

Answer 6

prone to develop any of the range of allergic syndromes, an atopic individual may begin life with eczema, go on to have allergies to milk/fish/eggs, develop asthma or hay fever.

Question 7

immediate hypersensitivity

Answer 7

Hypersensitivity refers to excessive, undesirable (damaging, discomfort-producing and sometimes fatal) reactions produced by the normal immune system. Hypersensitivity reactions require a pre-sensitized (immune) state of the host.

• requires IgE
• mast cell and basophils (amplified by platelets, NEs, EOs)

Question 8

allergy

Answer 8

“other response”, similar to atopic, atypical immune response to environmental antigens, eventually becoming characterized by increased reactivity or hypersensitivity of the end-organs to inflammatory mediators and irritants.

Question 9

allergen

Answer 9

something that triggers an allergy, the “antigen”, plants/flowers, dust, animal dander, tobacco smoke

Question 10

anaphylaxis

Answer 10

a severe, life-threatening Type I hypersensitivity reaction

Question 11

asthma

Answer 11

reversible bronchoconstrictive disease with progressive inflammation leading to fibrosis

Question 12

hives

Answer 12

redness, inflammation and edema of the skin associated with a Type I hypersensitivity reaction (urticaria is long term hives)

Question 13

wheal-and-flare reaction

Answer 13

development of a hive following intradermal injection of an allergen, diameter can be used for allergy testing

Question 14

State the approximate incidence of atopic diseases in the general population, and in individuals with allergic parents

Answer 14

a. Allergic diseases are among the most common conditions. Estimates as high as 20% of all people have allergies, but 15% seem more likely to experience allergic symptoms at some time in their lives. Allergic seasonal rhinitis is the most common, food allergy, eczema in children and asthma. Incidence of asthma nearly doubled from 1980 to 1995 (and the increase is REAL, not just better diagnostics).
b. Strong multifactorial genetic component. 1 allergic parent = 35% risk of developing allergy. 2 allergic parents= 65%.