Immunopathology type 2

Question 1

Direct antibody effects

Answer 1

autoantibody direct against cell surface receptor and behave as an agonist/antagonist
—> feedback don’t work because the end result does not affect antibody

ex: Graves (agonist) 
myasthenia gravis (antagonist)

Question 2

Complement mediated damage

Answer 2

antibody activates complement –> destruction of cells –> lysis, release of ROS, granules

ex: goodpasture’s
myasthenia gravis

Question 3

antibody dependent cell mediated cytotoxicity (ADCC)

Answer 3

NK cells bind Fc of IgG (on self)
Activates apoptosis of self cell

no immunizing exposure require
not MHC restricted

Question 4

Type II mechanism in muscle

Answer 4

Myasthenia gravis

antibody to Ach receptor of muscle
neutrophil damage at NMJ, no muscle contraction

Question 5

Type II mechanism in kidney

Answer 5

Goodpasture’s

autoantibodies to basement membrane of kidney –> persistent glomerulonephritis

Question 6

Type II mechanism in lung

Answer 6

Goodpasture’s

autoantibodies to basement membrane of lung –> pneumonitis and pulmonary hemorrhage

Question 7

similarity between lung and kidney

Answer 7

share antigen at basement membrane

goodpasture’s

Question 8

Type II mechanism in heart (1)

Answer 8

Rheumatic heart disease

after strep infection, antibody to strep M protein cross reacts with laminin on heart valve –> neutrophil destruction

Question 9

Type II mechanism in heart (2)

Answer 9

dressler’s syndrome

autoantibody to heart after MI

Question 10

Type II mechanism in red cells

Answer 10

autoimmune hemolytic anemia

viral infection/drugs –>
RBC coated with antibody –> opsonization/destruction

warm aiha = IgG
cold aiha = IgM

Question 11

Type II mechanism in platelets

Answer 11

autoimmune thrombocytopenic purpura

platelets opsonized and destroyed by antibodies –> bleeding

Question 12

Type II mechanism in thyroid (1)

Answer 12

hashimoto’s thyroiditis

antibodies against thryoid cells –> destroy hormone secreting cells –> hypothyroidism

Question 13

Type II mechanism in thyroid (2)

Answer 13

grave’s disease

antibody mimics TSH binding to TSH receptor –> hyperthyroidism

Question 14

type II mechanism in pancreatic islet cells

Answer 14

juvenile (type 1) diabetes

antibody to Beta cells in pancreas (produce insulin) –> activates complement –> destroys cell

Question 15

Direct test

Answer 15

1) patient’s kidney (already with antibody on glomerular basement membrane)
2) add goat fluorescent anti-IgG
3) if pt has goodpasture’s, linear binding on basement membrane

Question 16

indirect test

Answer 16

1) take a normal kidney biopsy
2) add patient serum
3) add goat fluorescent anti-IgG
4) antibody on basement membrane –> linear
antibody complex forms –> lumpy bumpy

Question 17

Linear immunofluorescent pattern

Answer 17

antibody is binding to a specific structure–> shows clear structure antibody is coating

= TYPE 2

Question 18

lumpy bumpy immunofluorescent pattern

Answer 18

immune complex formed, antigen and antibody clump together and precipitate

not line any particular strxr –> TYPE 3

Question 19

innocent bystander

Answer 19

neutrophils/macrophages try to destroy foreign antigen (bacteria) using ROS, granules, inflammation

in the process, attack normal adjacent host cells

Question 20

cross reaction of a foreign antigen with self

Answer 20

rheumatic heart disease

cross reaction between foreign antigen and self antigen
antibody coats normal self cells –> destroyed by complement

Question 21

coupling self antigen with a foreign antigenic carrier

Answer 21

1) anti-self B-cell escapes clonal deletion, binds self antigen + foreign antigen
2) since self + foreign, present foreign antigen via MHC II
3) Th cell recog foreign antigen, activate B cell to produce antibody to SELF ANTIGEN

(B-cells don’t necessarily see or get excited about the same antigens/epitopes as T-cells )

Question 22

Exposure of a sequestered antigen

Answer 22

normally, self antigens sequestered so immune system doesn’t see

but if immune response in the sequestered area, then immune cells attack self antigens

(blood-testis barrier)

Question 23

Inadequacy of regulatory T cells

Answer 23

insufficient Treg, so high Th1 and Th2 mechanism

causes tissue damage by hyperactive responses to normal antigens (food)

Question 24

Rheumatoid factor

Answer 24

IgM antibody against self IgG

agglutination of IgM and IgG

Question 25

Name condition in which antibody stimulates rather than inhibits its target cell

Answer 25

Graves disease (hyperthryoidsim)

LATS (IgG antibody that mimics TSH)
Binds TSH receptor to stim and secrete thyroid hormones
Normal feedback doesn’t work–> hyperthryoid

Question 26

AIRE gene involvement in preventing autoimmune

Answer 26

AIRE = causes thymic stromal cells to temporarily express peptides (found in the body) not native to thymus

anti-self T cells destroyed before reach circulation