Allergic Reacitions

Question 1

Which type of allergic reaction is mediated by IgE?

Answer 1

Type I

Question 2

Which type of allergic reaction is mediated by IgM or IgG?

Answer 2

Type II, cytotoxic

Question 3

Which type of allergic reaction is mediated by Ab-Ag complexes?

Answer 3

Type III

Question 4

Which type of allergic reaction is mediated by T-cells?

Answer 4

Type IV

Question 5

True or False: The severity of acute phase reaction in Type I hypersensitivity is a predictor of severity of the last phase.

Answer 5

True, since more cytokines get released, leading to more baso and eos activation.

Question 6

Goodpastures and Myesthenia gravis are examples of which type of hypersensitivity reaction?

Answer 6

Type II

Question 7

Leukoclastic vasculitis is a generic term associated with which type of hypersensitivity?

Answer 7

Type III

Question 8

In general, what is the difference between the way serum sickness and Arthus reaction are triggered.

Answer 8

In serum sickness, un-immunized host gets a large amount of Ag. In Arthus reaction, hyper-immunized host gets Ag injection.

Question 9

Serum sickness is an example of which type of hypersenitivity?

Answer 9

Type III

Question 10

Hymenoptera stings can cause Type 1 as well as this other type of hypersensitivity.

Answer 10

Type III leading to serum sickness.

Question 11

What is the description of the rash commonly associated with serum sickness?

Answer 11

Serpiginous rash of hands and feet.

Question 12

What is the Arthus reaction?

Answer 12

A local reaction at the site of innoculation, caused by Type III hypersensitivity. The host is hyper-immunized to the offending Ag.

Question 13

Nickel allergy is classically what type of hypersensitivity? Name another common example of this type.

Answer 13

Type IV. The tuberculin reaction is also type IV.

Question 14

Graves is similar to Goodpastures and Myesthenia Gravis in that it is caused by a hypersensitivity reaction, but it isn’t grouped with them. Why? What type of reaction are they? What type of reaction is Graves?

Answer 14

They are Type II and are different because Graves (Type V) is a disease that is caused because of ACTIVATION by the Ab-Ag complex. In type II, there is cytotoxic destruction because tissue gets inappropriately tagged with Ab.

Question 15

Urogenital malformations are associated with allergy to what substance?

Answer 15

Latex

Question 16

Which complement molecules are anaphylactoid?

Answer 16

C3a, C4a, C5a

Question 17

Which substances are associated with anaphylactoid reactions?

Answer 17

Aspirin, NSAIDs, contrast, sulfites

Question 18

How is anaphylaxis and anaphylactoid the same? Different?

Answer 18

Both involve mast cell degranulation. However, anaphylactoid is NOT IgE mediated.

Question 19

What is the treatment of anaphylactic and anaphylactoid reactions?

Answer 19

Epinephrine! 0.01 mg/kg 1:1000 concentration.

Question 20

What would you do if you had a patient on beta blockers who was given epinephrine for anaphylaxis and had a blunted response?

Answer 20

Give second-line agents like glucagon and vasopressin. The point is that you would still have epi as first line therapy.

Question 21

What are some differences in acute vs. chronic urticaria (in terms of duration of symptoms, triggers?)

Answer 21

Acute urticaria are generally IgE mediated and triggers are typical allergies. Chronic last 4-6 weeks, 90% idiopathic, and causes including thyroid, autoimmune, malignancy and chronic infection.

Question 22

A 13 year old girl is seen in your office with punctate hives that are very pruritic. They come and go. What HPI questions would help you sort out the cause?

Answer 22

Does this just occur with showering? Heat triggers cholinergic urticaria, described like this vignette.

Question 23

There is one type of urticaria that is not benign and often gets missed. Which is it? What are some red flags associated with this condition?

Answer 23

Urticarial vasculitis. Red flags:

• Lesions > 24 hours
• Lesions that are fixed location.
  Residual ecchymosis, hyperpigment, or purpura.
• Non-pruritic, tender, burning
• Arthritis, fever, fatigue

Question 24

What are some diagnostic features in urticarial vasculitis?

Answer 24

Skin bx diagnosis it but C3/C4 will usually be low and there may be antibodies to C1q.