Immunology

Question 1

What agents are typically used for induction (such as for a new transplant) and what are their mechanisms?

Answer 1

• Alemtuzumab: an anti-CD52 antibody that depletes lymphocytes (referred to as “liquid AIDS”)
• Corticosteroids: decrease T cell activation
• Thymoglobulin: anti-thymocyte antibody that attacks T cell production

Question 2

What agents are typically used for maintenance of immunosuppression and what are their mechanisms?

Answer 2

• Calcineurin inhibitors that decrease T cell activation: cyclosporine and tacrolimus
• Mycophenolate mofetil that decrease lymphocyte proliferation

Question 3

List the types of prophylaxis that organ-transplant patients need.

Answer 3

• CMV if they in a high-risk category (use Valcyte)
• Pneumocystis if they are on steroids (use Bactrim if not G6PD deficient, use dapsone or inhaled pentamidine if they are G6PD deficient)
• There is no ppx for EBV but it is good to be aware of their status (e.g., D+/R- or D-/R+) because they can have reactivation.

Question 4

True or false: all organ-transplant patients require chronic prednisone.

Answer 4

False

Typically only those who have had confirmed or suspected rejection require long-term steroids.

Question 5

The original name for rapamycin was _____________.

Answer 5

sirolimus

Question 6

Review the management of allergic reaction and anaphylaxis.

Answer 6

• Always give an H1 and H2 blocker. These are safe medicines and have essentially no reason not to give them in an allergic reaction.
• Give epinephrine and steroids for anaphylaxis, which is more than one organ system involvement.
• Give albuterol if wheezing is present.
• Observe for at least four hours.

Question 7

What is the weight cutoff for Epi Pen Jr?

Answer 7

< 30 kg

Question 8

Review all the agents available for anaphylaxis.

Answer 8

Epinephrine
Antihistamines (H1 and H2 blockers)
Steroids
Glucagon (this works to increase adrenergic tone through the cAMP pathway, not the receptor-mediated pathway)

Question 9

Review the mechanism of IgE mediated reaction.

Answer 9

Type I reactions happen when IgE binds to an antigen. Mast cells then bind to IgE and degranulate, releasing histamine and other vasoactive mediators.

Question 10

Immune complex deposition is a type ______ immune reaction.

Answer 10

III

Question 11

DRESS is a type ______ immune hypersensitivity reaction.

Answer 11

IV (T-cell mediated)

Question 12

Which cells are responsible for acute and chronic transplant rejection?

Answer 12

Acute is CD8, chronic is CD4

Question 13

What is the pediatric dose of epinephrine for anaphylaxis?

Answer 13

0.01 mg/kg IM up to a max of 0.3 mg

Example: a 12 kg toddler (like June) would need 0.12 mg IM. Her auvi-q is 0.1 mg.

Question 14

What three classes of medications can induce angioedema?

Answer 14

ACEi
NSAIDs
tPA

Question 15

How is the swelling of angioedema different from anaphylaxis?

Answer 15

Angioedema is well demarcated

Question 16

Unlike urticaria, angioedema is usually __________.

Answer 16

non-pruritic

Question 17

Why might you give anaphylaxis medicines to those with angioedema?

Answer 17

There are histamine-mediated forms of angioedema as well as angioedema-anaphylaxis overlap syndromes that respond to anaphylaxis treatment.

Question 18

Why might you give FFP to someone having angioedema?

Answer 18

Although evidence is poor, FFP has ACE in it so can hypothetically relieve ACEi-induced angioedema. FFP also has bradykinin in it, though, so might worsen bradykinin-induced angioedema.

Question 19

The three pathophysiologies of angioedema are what?

Answer 19

Histamine-mediated
Bradykinin-mediated
Idiopathic

Question 20

Those with hereditary angioedema can receive what targeted therapies?

Answer 20

Concentrated C1 esterase inhibitor
Icatibant (bradykinin receptor antagonist)
Kallikrein inhibitors such as ecallantide

Question 21

How can the history help you figure out which type of angioedema is present (i.e., histaminergic or bradykinin-mediated)?

Answer 21

• Medication-induced angioedema (such as ACEi, NSAIDs, or tPA) is typically bradykinin-mediated
• Envenomation is usually histaminergic
• Pruritis and urticaria are usually seen in histaminergic angioedema

Question 22

What cause of angioedema do you need to consider in those with a first-time case of angioedema who are older than 40?

Answer 22

Malignancy (typically lymphoproliferative)

Question 23

True or false: angioedema is usually non-pruritic.

Answer 23

True

Question 24

In hereditary angioedema, what protein is missing?

Answer 24

C1 esterase inhibitor