Practice #11

Question 1

What are the 3 options of type 2 hypersensitivity reactions?

Answer 1

1. Binding of autoreactive IgG to cell surface epitopes recognizeg by Fc gamma RIII on NKC and macrophages
2. Binding of autoreactive IgG to matrix components and complement activation
   Both result in cell lysis or tissue injury
3. binding of autoreactive IgG to receptors on the cell surface altering cell signaling

Question 2

Examples for extrinsic (systemic) antigen depositin

Answer 2

Erythroblastosis fetalis, transfusion reaction, hyperacute allograft rejection, drug induced hemolytic anemia

Question 3

Examples for intrinsic (localized) antigen depositin

Answer 3

Myesthenia gravis, Grave’s Basadow’s disease

Question 4

Coombs test

Answer 4

Direct: Detect antibodies on the surface of red blood cells for ex: drug induced hemolytic anemia
Indirect: Detect free antibodies in the serum (anti D in Rh- maternal serum)

Question 5

3 Advantages in the anti D passive immunization during Rh incompetability

Answer 5

1. High amount of IgG will inhibit B cells by Fc gamma RIIB
2. H levels of anti D IgGs will neutrilize the antigen and mask it
3. Interaction of IgG with D antigen will result in the phagocytosis and elimination of the antigen

Question 6

Type 3 hypersensitivity reaction will eventually lead to tissue damage, by what mechanisms?

Answer 6

1. Complement activation

2. Frstrated phagocytosis

Question 7

The EFFECTOR mechanism of tissue damage in Type 3 hypersensitivity reaction depends on

Answer 7

1. Size of IC
2. Ratio between Ag-Ab
3. Affinity of the Ab
4. Isotype of the Ab

Question 8

The CONCEQUENCE of tissue damage in Type 3 hypersensitivity reaction depends on

Answer 8

The site of deposition

Question 9

Examples for local type 3 hypersensitivity reactions

Answer 9

Vasculitis, pneumonitis

Question 10

Examples for acute systemic type 3 hypersensitivity reaction

Answer 10

Acute serum disease

Question 11

Examples for chronic systemic type 3 hypersensitivity reaction

Answer 11

SLE, RA

Question 12

Type 4 hypersensitivity reaction sequence of events

Answer 12

1. Antigen recognition in lymphois organs
2. T cell expansion and diferentiation
3. Effector T cells get to the site of infection
   and activate macrophages (by IFN gamma)
4. Macrophages are activated secreting cytokines and chemokines further attracring lymphocytes and macrophages

Question 13

Examples for Type 4 hypersensitivity reactions

Answer 13

1. Delayed type: TB
2. Contact: Haptens
3. Celiac disease

Question 14

Gluten sensitive enteropathy (Celiac disease)

Answer 14

Th2 cell mediated atrophy (90-95% carry HLA-DQ allelic variant)
For diagnosis we look for:
1. Anti tissue transglutaminase IgA
2. Anti endomesyum IgA
3. Anti deaminated gliadin IgA and IgG
4. Anti gliadin antibody IgA and IgG