Dr Mai-Immunopathology

Question 1

What is Hypersensitivity?

When it happens?

Answer 1

• Excessive,undesirable reactions produced by the immune system.
• 2nd time

Question 2

what is Immunodeficiency ?

Answer 2

-Defect in 1/more components of immune system

Question 3

What are allergens?

Answer 3

-Is a substance that produces an allergic response

Question 4

Immune complexes consist of

a. antibody plus complement
b. basophil plus complement
c. antigen plus antibody
d. antigen plus complement

Answer 4

c. antigen plus antibody

Question 5

Blood transfusion hypersensitivity reactions are examples of:

a. Type IV hypersensitivity
b. Type III hypersensitivity
c. Type II hypersensitivity
d. Type I hypersensitivity

Answer 5

c. Type II hypersensitivity

Question 6

A hypersensitivity reaction occurs

a. During the first exposure to an antigen
b. During a second or subsequent exposure to an antigen
c. In individuals with the disease of the immune system
d. none of above

Answer 6

b. During a second or subsequent exposure to an antigen

Question 7

4. A possitive tuberculin test is an example of what type of hypersensitivity reaction ?
   a. Type IV hypersensitivity ( No memory B cells)
   b. Type III hypersensitivity
   c. Type II hypersensitivity
   d. Type I hypersensitivity

Answer 7

a. Type IV hypersensitivity ( No memory B cells)

Question 8

5. What 2 isotypes of antibody can cause type II and type III hypersensitivity diseases?

Answer 8

IgM and IgG

Question 9

6. List name of 5 common allergens can cause the anaphylactic reaction?

Answer 9

1. Atopic dermatitis (children)
2. Milk allergy (Jersey cattle)
3. Allergic inhalant dermatitis ( Terriers and Dalmatian dogs)
4. Fever (human)
5. Asthma (human)

Question 10

7. Why is desensitization therapy used in type I hypersensitivity ?

Answer 10

Because this therapy can :
-Reduce mediator release from Mast cells
-Decrease the number of Mast cells in tissues
-Decrease serum IgE levels on Mast cells and produce
blocking antibody IgG

Question 11

8. What is the result of the actions of mast cell mediators in anaphylaxis? (2marks)

Answer 11

Advances in mast cell signaling research have improved our understanding of the pathophysiology of anaphylaxis. The identification of signaling pathways and components that amplify signals or alter the threshold of activation of mast cells, leading to degranulation and mediator release, has the promise of identifying novel approaches for prevention and treatment of anaphylaxis. The discovery of polymorphisms and mutations in components that regulate mast cell signaling might lead to ways to identify subjects who are most susceptible to life-threatening episodes of anaphylaxis caused by mast cell activation

Question 12

9. What are the 2 main mechanisms causing injury in anti-tissue ( Type II hypersensitivity) disease? (2)

Answer 12

-Complement Activation
Recall that cross-linked antibodies normally activate the Classical Pathway of the Complement Cascade. This results in the generation of the membrane-disrupting “Membrane Attack Complex” or causes opsonization of the material with C3 which recruits other immune cells to phagocytose the opsonized material. When antibodies target host cells, complement activation can cause direct injury to the host cells as well as induce potent inflammation and phagocytic destruction of host tissue

-Antibody-mediated Cell-mediated Cytotoxicity (ADCC)
Once cross-linked onto antigen, the Fc Region of antibody normally recruits a number of phagocytic immune cells such as macrophages and neutrophils which are then activated to phagocytose the opsonized material. When antibodies target host membranes this can result in substantial inflammation and phagocytic destruction of host tissues.

Question 13

10. What is immunodeficiency ? What are the most common causes of immunodeficiency? (3)

Answer 13

• A genetic or acquired defect results in an inability to mount an immune response and thus control infections, resulting in severe systemic inflammation.
  - Primary immunodeficiency: the result of a congenital or genetic defect in a component of the immune system. Although the defect may be present at birth, the disease may not be manifested until later in life

Question 14

11. What is the mechanism of Type II Antibody-Mediated Cytotoxic Disorders?

Answer 14

IgG or IgM antibodies bind to antigens on the cell surface and destroys or prevents the cell from functioning

Question 15

12. What are the specific ways the target cell is destroyed or disabled in Type II Antibody-Mediated Cytotoxic Disorders?

Answer 15

1. Complement mediated lysis
2. Phagocytosis
3. Neutrophil mediated

Question 16

13. How does complement mediated cell lysis function in Type II Antibody-Mediated Cytotoxic Disorders?

Answer 16

• Antibody binds to the antigens on the target cell
• Antibody combines with C5-9 complex (from the complement system) to form MEMBRANE ATTACK COMPLEX
• Membrane attack complex causes cell lysis

Question 17

14. How does phagocytosis function in Type II Antibody-Mediated Cytotoxic Disorders?

Answer 17

• Antibody binds to antigen on surface of target cell
• Antibody also activates the complement system, which causes C3b to be deposited on the cell surface
• Cb3 causes opsonization, which makes it easier for macrophages to phagocytize the target cell

Question 18

15. How does antibody dependent cell lysis function in Type II Antibody-Mediated Cytotoxic Disorders?

Answer 18

• Antigens on the surface of the target cell bind with antibodies
• Natural killer T cells bind with the antibodies and kill the cell
• *** This mechanism DOES NOT NEED COMPLEMENT

Question 19

16. What is the mechanism for Type III immune-Complex Disorders?

Answer 19

• Antigens circulating freely get bound to antibodies
• This forms insoluble antigen-antibody (A-A) complexes
• The A-A complexes get deposited in vessel walls and tissues
• This activates complement, which leads to recruitment of neutrophils
• Causes acute inflammation and tissue damage

Question 20

17. What is serum sickness and what are the symtoms?

Answer 20

• A type III Immune-Complex Disorder
• Horse serum was used in tetanus antitoxin
• The horse serum acts as the foreign body (antigen)
• Symptoms of serum sickness include:
• Rash
• Lymphadenopathy (swollen lymph nodes)
• Arthralgia (joint pain)
• Symptoms usually occur 7 days post exposure

Question 21

18. What are the mechanisms of Type IV Cell Mediated Disorders?

Answer 21

• NO ANTIBODIES OR COMPLEMENT
• Type IV is mediated by T lymphocytes:
• Cytotoxic T Lymphocytes (Tc)
• Cytokine producing Th1 cells.

Question 22

Autoimmunity?

Answer 22

The failure of an individual in RECOGNIZING ITS OWN CONSTITUENT PARTS AS SELF,=> AN IMMUNE RESPONSE AGAINST ITS OWN CELLS N TISSUE

Question 23

Player in type 1 hypersensitive ( IgE-mediated hypersensitive)

Answer 23

IgE,mast cells and basophils

Question 24

Type I hypersensitive is caused by

Answer 24

Allergens

Question 25

What are allergens?

Answer 25

• drugs: penicillin, sulfonamides, vaccine
• insect products: bee venom, wasp venom, ant venom
• rye grass, timothy grass, ragweed;…
• mold spore, dust mites, animal hairs

Question 26

If an immediate hypersensitivity reaction is systemic and life-threatening that is called ?

(life-threatening=fatal=a life-threatening situation, illness, or injury could cause a person to die)

Answer 26

-allergic anaphylaxis or anaphylactic shock.

Question 27

atopy(n)

atopic(adj) effected individuals

Answer 27

The excessive production of IgE