Type III Immunopathology

Question 1

What three requirements must be met in order to see a type III immunopathology?

Answer 1

The immune complex must…

1. Be to small to removed by RED
2. Large enough to activate complement
3. Too large to readily pass through basement membrane

Question 2

What components of complement recruit neutrophils?

Answer 2

C3a and C5a

Question 3

Name somethings that neutrophils release upon arrival to immune complexes stuck in a basement membrane.

Answer 3

Inflammatory factors like proteases cathepsin G and elastase and hydrogen peroxide

Question 4

What activates metalloproteinases?

Answer 4

Hydrogen peroxide

Question 5

What three things contribute to degradation of the basement membrane?

Answer 5

Proteases cathepsin G (produced by neutrophils)
Elastase (produced by neutophils)
Metalloproteinases

Question 6

What helps release histamine from mast cells?

Answer 6

C3a and C5a

Question 7

Type III immunopathology causes what?

Answer 7

Widespread small vessel vasculitis

Question 8

Polyarteritis nodosa can be caused by what virus?

Answer 8

Hepatitis B and C

-Viral proteins + antibodies embed in medium sized arteries

Question 9

Can an antigen that is quickly cleared by the body cause Type III?

Answer 9

No. The antigen needs to be given in a high enough quantity so it can be around when the antibody is finally made by the B cells

Question 10

What is the onset of serum sickness?

Answer 10

10-14 days after exposure. Need time for the antibodies to be released. 10-14 is the time it takes for the antigen to still be in a little bit of excess of the antibody -

Question 11

What are the symptoms of serum sickness?

Answer 11

Fever
malaise
rash + itch
arthraligia

Question 12

True or Flase

Serum sickness can happen after treatment with murine, chimeric, or humanized monoclonal antibodies

Answer 12

True

Question 13

How can penicillin cause a type III reaction?

Answer 13

Penicillin can be know to bind to human peptides.

Complex taken up by B cells and digested and presented to T cells

T cells recognize penicillin + chewed up protein and activates B cell switching

B cell creates anti-penicillin antibodies

Complexes form

Question 14

True or False:

Serum sickness-like symptoms can be seen in patients with viral infections like hepatitis

Answer 14

True. 
Lower-leg rash
Malaise 
Fever
Arthralgias

Question 15

An 8 year old boy comes into the emergency room complaining of nausea, vomiting, fever, malaise, hypertension. reduced urine output,hematuria, and joint pain. What should be your next question?

Answer 15

Have you had a soar throat lately because it sounds like acute post-streptococcal glomerulonephritis.

Question 16

What is the treatment for someone with acute post-streptococcal glomerulonephritis?

Answer 16

Antibiotics and supportive care

Question 17

What would you see on the labs of a patient with acute post-streptococcal glomerulonephritis?

Answer 17

Hematuria

Decreased complement levels

Question 18

A farmer comes in with a dry cough, malaise, fever and tachycardia. It has been raining lately What should be on your differential?

Answer 18

Hypersensitivity pneumonitis. caused by thermophilic Actinomycetes found in moldy hair. Aerosolized spores are inhaled complexes form in the lunges

Question 19

What is the treatment of hypersensitivity pneumonitis?

Answer 19

Systemic glucocorticoids and avoidance

Question 20

A booster immunization is given to a child. The injection site becomes inflammed. What has just occured?

Answer 20

Arthus reaction. Pre-existing antibody to immunogen complexes immediately begin to form locally.

Question 21

Can antigens be endogenous?

Answer 21

Yes

Question 22

Rheumatoid factor is an IgM anti-IgG, but it is just big enough to deposit in the BM. So what type of reaction it this?

Answer 22

Type III

Question 23

Describe the pathogenesis of systemic lupus erythematosus.

Answer 23

Antibodies to double stranded DNA
HIstones H2, H3, and H4.

The antibody—dsDNA preferentially deposit in kidneys

Question 24

Why do SLE patients develop facial butterfly rashes?

Answer 24

Sun-damaged DNA-releasing skin cells + reactive antibodies

Question 25

What is the leading reason for kidney transplatation?

Answer 25

IgA Nephropathy.

Question 26

What causes IgA nephropathy?

Answer 26

Terminal sugars of the carbohydrate chains in the hinge of an IgA are missing creating a new epitope that looks like those found in bacteria and viruses.

Antibodies bind and the complexes deposit in the basement membranes of kidneys

Question 27

What are some causes of IgA nephropathy?

Answer 27

Chronic tonsillitis and maybe some genetic causes

Question 28

How can you diagnose Type III?

Answer 28

1. Low total hemolytic complement
2. Cryoglobulins
3. Rheumatoid factor
4. Renal biopsy

Question 29

What are cryoglobulins?

Answer 29

Fluffy precipitate when the serum is kept 24 hours in the rerigerator (immune complexes which are less soluble in the cold)

Question 30

Visualizing a renal biopsy with fluorescein-labeled goat antibodies to human immunoglobulin would show what type of pattern if the pathology was Type III?

Answer 30

Lumpy bumpy