Chapter 12 ( Hypersensitivity And Autoimmune Diseases )

Question 1

Type l hypersensitivity immune mechanism ? Mechanism of tissue injury ?

Answer 1

Activation of Th2 resulting in the production of IgE which binds to FceR on mast cells , basophils and eosinophils

Immediate reaction : degranulation and release of vasoactive amines and proteases
Late-phase reaction : synthesis and secretion of prostaglandins and leukotrienes , cytokine-induced inflammation and leukocyte recruitment

Question 2

Type ll hypersensitivity immune mechanism ? Mechanism of tissue injury ?

Answer 2

IgM and IgG against surface ( cell surface or extracellular matrix )

Complement mediated cytotoxic :
Opsonization and enhances phagocytosis
Recruitment and activation of inflammatory cells

Non-cytotoxic :
Change in physiologic behavior of a cell

Question 3

Type lll hypersensitivity immune mechanism ? Mechanism of tissue injury ?

Answer 3

Deposition of immune complexes comprised of IgG or IgM and soluble antigen

Complement mediated recruitment and activation of inflammatory cells resulting in some combination of arthritis , vasculitis and/or nephritis

Question 4

Type lV hypersensitivity immune mechanism ? Mechanism of tissue injury ?

Answer 4

Inflammatory cytokines INF-gamma and IL-17 produced by Th1 and Th17 respectively

Cytokine mediated tissue damage :
INF-gamma activation of macrophages
IL-17 recruitment and activation of neutrophils

Direct killing : CTL-mediated cellular death

Question 5

Mast cell mediators ?

Answer 5

Mediators stored and releases :
Histamine
Heparin
Eosinophil chemotactic factor A

Mediators newly synthesized from arachidonic acid :
Prostaglandin D2 , E2 , F2alpha
Leukotrienes C4 , D4 , E4
Leukotriene B4

Question 6

Allergic diseases due to specific allergens ?

Answer 6

Allergic rhinitis 
Systemic anaphylaxis
Food allergies 
Wheal and flare 
Asthma

Question 7

Examples for type ll hypersensitivity ?

Answer 7

Cytotoxic :
Autoimmune hemolytic anemia 
Acute rheumatic fever 
Good pasture syndrome 
Transfusion reaction 
Autoimmune thrombocytopenic purpura

Non-cytotoxic : 
Myathenia gravis 
Graves disease 
Type ll diabetes 
Pernicious anemia

Question 8

Examples for type lll hypersensitivity ?

Answer 8

Systemic lupus erythematosus 
Poststreptococcal glomerulonephritis 
Arthus reaction 
Serum sickness 
Polyarteritis nodosa

Question 9

Serum sickness antigen ? Symptoms ?

Answer 9

Various proteins

Arthritis
Vasculitis
Nephritis

Question 10

Antibodies in Sjörgen syndrome against what ?

Answer 10

Ribonucleoproteins

Question 11

Antibodies in diffuse systemic sclerosis against what ?

Answer 11

DNA topoisomerase 1

Question 12

Antibodies in CREST against what ?

Answer 12

Centromeric proteins

Question 13

Antibodies in rheumatoid arthritis ?

Answer 13

Rheumatoid factor ( IgM against Fc region of IgG ) 
Alpha-cyclic citrullinated peptide (alpha-CCP) antibodies

Question 14

Examples for type lV hypersensitivity ?

Answer 14

Tuberculin test 
Contact dermatitis 
Hashimoto thyroiditis 
Multiple sclerosis 
Rheumatoid arthritis 
Type l DM 
GB syndrome 
Celiac disease 
Crohn disease

Question 15

The 3 primary mechanisms that induce peripheral tolerance ?

Answer 15

Anergy
Deletion
Suppression

Question 16

Anergic B lymphocytes ?

Answer 16

B lymphocytes that recognize self-antigen in the absence of T cell signaling and express high levels of IgD on their surface excluding them from secondary lymphoid tissues

Question 17

Cause of T cell anergy ?

Answer 17

A break down in either :
TCR signaling
The binding of an inhibitory receptor CTLA-4 or PD-1

Question 18

Mechanism of deletion of self reactive T lymphocytes ?

Answer 18

Apoptosis by activation of the caspase signaling pathway or Fas signaling pathway

Question 19

HLA allele of RA ?

Answer 19

DR4

Question 20

HLA allele of type l DM ?

Answer 20

DR3/DR4

Question 21

HLA allele of multiple sclerosis and Goodpasture’s syndrome ?

Answer 21

DR2

Question 22

HLA allele of SLE ?

Answer 22

DR2/DR3

Question 23

HLA allele of ankylosing spondylitis , psoriasis , IBD , reactive arthritis ?

Answer 23

B27

Question 24

HLA allele of celiac disease ?

Answer 24

DQ2 or DQ8

Question 25

HLA allele of Graves disease ?

Answer 25

B8