Allergy/immunology

Question 1

What type of hypersensitivity reaction is anaphylaxis? How many systems need to be involved? Treatment?

Answer 1

Type 1, IgE mediated
2 systems ( must include cutaneous unless exposure to known allergen, GI, respiratory including upper respiratory sx, CV)
Rx: epinephrine dose is 0.01 mg/kg IM q 5 mins to a max of 0.5 per dose

Question 2

What is the dose of epinephrine for anaphylaxis?

Answer 2

0.01 mg/kg IM q 5 mins (to a max of 0.5mg/dose)
Also give antihistamine
Steroids controversial

Question 3

When is the physiologic nadir of maternal IgG ?

Answer 3

4 months of age - when primary immunodeficiencies present

Question 4

What are the screening tests for immunodeficiency?

Answer 4

CBC with diff
Flow cytometry
Immunoglobulins (and albumin)
Response to vaccines (tetanus and pneumococcal titres)
HIV testing

Question 5

List the early onset immunodeficiencies and when do they present?

Answer 5

Present at 3-6 months at maternal IgG nadir
-Brutons (X linked) agammaglobulinemia
-Hyper IgM - also x linked, only make IgM

Question 6

What are the diagnostic criteria for CVID

Answer 6

Recurrent infections
Low IgA and IgG
Non protective titres
B cell low/normal

Question 7

Which cells are failing in SCID and what is the diagnostic criteria

Answer 7

T cells failing, <300
TREC screen abnormal (NBS)
Absent/low CD45RA naive T cells
Absent proliferation of T cells to mitogen

Question 8

Which genetic syndromes are associated with SCID?

Answer 8

X linked common gamma chain
Digeorge 22q11
CHARGE syndrome

Question 9

how long after exposure does serum sickness usually present

Answer 9

1-2 wks

Question 10

Which type of hypersensitivity reaction is responsible for DRESS?

Answer 10

Type IV ( T cell)

Question 11

Which of the hypersensitivity reactions require treatment with steroids?

Answer 11

DRESS
Steroids improve mortality

Question 12

You are caring for a 2 year old child with bronchiolitis. Her mother notes she has been “sick practically half of the time!” and details 9 respiratory infections over the past year. The child has normal development, normal exam save for her current respiratory symptoms, and a normal newborn screen. This is the first time the child has been hospitalized. She has never required IV antibiotics. Between illnesses she recovers completely, albeit briefly. What is the next step in your work up?

Answer 12

Reassurance. This is a normal child.

Question 13

The immune system is most broadly divided into which two categories?

Answer 13

Adaptive and Innate Immunity

Question 14

Adaptive immunity is broadly divided into which two categories?

Answer 14

Humoral and cell mediated.

Question 15

Humoral and cell mediated immunity are predominantly related to the function of which two types of immune cells, respectively?

Answer 15

B cells (humoral) and T cells (cell mediated)

Question 16

You are caring for a 4 year old child with recurrent sinusitis who has now been hospitalized twice this year for bacterial pneumonia. You should be most concerned about a defect with which type of immune cell?

Answer 16

B-cells (humoral immunity)

Question 17

You are caring for a 3 year old child who has had multiple bouts of diarrhea over the past 6 months and has also needed to be treated three times for thrush. You should be most concerned about a defect with which type of immune cell?

Answer 17

T-cells (cell-mediated immunity)

Question 18

Humoral immunity is mainly responsible for response to what kind of pathogens?

Answer 18

Extracellular.

Question 19

Cell mediated immunity is mainly responsible for response to what kind of pathogens?

Answer 19

Intracellular (mainly viruses). Bonus: cell mediated immunity is also responsible for surveillance for cancer cells.

Question 20

Your patient has developed mucosal ulcerations, cracked bleeding lips, and a few target like lesions on arms and palms. He recently recovered from a persistent cough. What is the diagnosis and what is the treatment?

Answer 20

Mycoplasma pneumoniae-induced rash and mucositis. Treatment is supportive care. Steroids are often used but there is no evidence this is effective.

Question 21

You are caring for a 16 year old patient with pyelonephritis. Her friends bring in a salad from an outside restaurant. Unbeknownst to her, the salad has cashews which she is allergic to. She presses the the call light and tells the nurse “I don’t feel very well and I think I just ate some cashews. And I’m allergic to cashews.” The nurse checks here blood pressure. It is 80/30. Does this patient meet criteria for anaphylaxis?

Answer 21

Yes. After exposure to a known allergen, hypotension alone is sufficient to diagnose anaphylaxis.

Question 22

Describe the four categories of primary immunodeficiency.

Answer 22

-B cell: e.g. agammaglobinemia, CVID
-T cell: e.g. SCID, DiGeorge, ataxia telangiectasia, wiskott aldrich.
- Complement: various complement deficiencies like c1, c2, c3, c4, c5-c9
- Phagocytosis: e.g. CGD

Question 23

Name 4 examples of primary immunodeficiency related to T-cell deficiency

Answer 23

SCID, DiGeorge, Wiskott Aldrich, Ataxia telangiectasia

Question 24

Both B-Cell deficiencies and phagocytic cell defects can present with repeated infections by encapsulated organisms. What features distinguish them?

Bonus: List the encapsulated bacteria

Answer 24

Mucosal changes, delayed wound healing, abscesses (CGD)
Autoimmune diseases, failure to thrive (B-cell defects).

Encapsulated bacteria: Yes some killer bacteria have pretty nice capsules
(Yersenia, strep pneumo, klebsiella, bacillus anthracic, H flu, pseudomonas, neisseria, cryptococcus)

Question 25

Your patient has mucosal changes affecting mouth and GU region, and target lesions evolving to desquamation affecting trunk and extremities with 35% BSA affected. What treatment is most likely to improve the extent and duration of symptoms?

Answer 25

Growing evidence suggests cyclosporine may be useful in the treatment TEN. There is insufficient evidence that IVIG or steroids are helpful, and steroids may in fact be harmful.

Question 26

Describe the clinical presentation of FPIES and list common causes. What is the treatment?

Answer 26

Food Protein induced enterocolitis syndrome
Vomiting, diarrhea, pallor, hypotension/shock, lethargy. Notably no rash or respiratory symptoms
Acute or chronic. Eosinophilia may be present. NOT IgE mediated.
Eggs, Soy, Rice, poultry/fish
Rx: fluid resuscitation, supportive care. stop ingestion of offending agent.

Question 27

What is the treatment for SCID?

Answer 27

Temporizing with antibiotics and IVIG followed by bone marrow transplant.

Question 28

What is the treatment of CVID?

Answer 28

IVIG and antibiotics for treatment of, and possible prophylaxis against, infections.

Question 29

What antibiotic will provide prophylaxis against PCP, Strep, and Staph (including some MRSA) in immunocompromised patients?

Answer 29

Sulfamethoxazole-trimethoprim

Question 30

How can thrombocytopenia due to Wiskott Aldrich syndrome be distinguished from ITP?

Answer 30

1. Platelets are small in WAS, large in ITP
2. WAS is typically also accompanied by severe eczema and repeated infections by encapsulated organisms and viruses.

Question 31

What laboratory findings are observed in Wiskott Aldrich syndrome, including immunoglobin subtypes?

Answer 31

1. High IgA and IgE
2. Normal or low IgG and IgM
3. Thrombocytopenia with small platelets.
4. Decreased T-cells
5. Diagnosis is ultimately by sequencing of WAS gene to identify mutation.

Question 32

How is Wiskott Aldrich Syndrome treated?

Answer 32

1. Temporizing with IVIG
2. PCP and HSV prophylaxis with bactrim and acyclovir
3. Bone marrow transplant

Question 33

You are caring for a vaccinated 3 year old child who presents with lobar pneumonia secondary to strep pneumo infection. She has had multiple sinopulmonary infections, and was treated for osteomyelitis six months ago. What class of lymphocytes are likely defective in this child, and what are the most common diagnoses?

Answer 33

1. B-cells
2. Aggamaglobulinemia, Hyper-IgM, CVID