Allergy/Immunology Flashcards
What is required to be considered “high risk” for allergic disease?
- Personal history OR 1˚ relative with atophy
- Food allergy
- Allergic rhinitis
- Asthma
- Eczema
When should solids be introduced for average risk vs high-risk allergic children?
When introducing allergenic foods, what 2 things would you advise parents to do?
- Average risk = 6 months
- High-risk = 4-6 months
Introducing Allergenic foods
- Introduce one at a time, without unnessary delay between each food (1-2 days)
- If well tolerated, offer it a few times a week to maintain tolerance
- If adverse reaction observed, consult with PCP about next steps or if signs of anaphylaxis go to ED.
List 5 common food allergens
- Cow’s milk
- Egg
- Peanuts
- Tree nuts
- Fish
- Shellfish
- Wheat
- Soy
What type of immunodeficiencies present with sinopulmonary infections?
- B cell defects (ie. IgA deficiency, CVID, Agammaglobulinemia)
- T cell defects (ie. SCID, DiGeorge, Ataxia-Telangiectasia, APECED)
Other DDx:
- Primary ciliary dyskinesia
- BPD/CLD
- Cystic fibrosis
- Anatomic defect (ie. CCAM)
- Allergic rhinitis
- Social factors (ie. smoking, daycare, older siblings, etc)
- Secondary immunodeficiency (ie. immunosuppression, nephrotic syndrome, protein losing enteropathy, HIV, malnutrition, T21, malignancy)
List 4 immunocompromised medical conditons
- Post-HSCT (within 2y or still taking immunosuppressive drugs)
- Solid-organ transplant (lung, heart, kidney, liver, pancreas)
- Malignancy: current or recently treated
- Aplastic anemia
- Asplenia/functional asplenia
- HIV (CD4 <5yo: <15%; ≥5yo: <200)
- SCID
- Taking the following medications
- Chemotherapy
- High-dose corticosteroids (>2mg/kg for ≥2wks)
- Biologics
- Antimetabolites (e.g. azathioprine)
- Transplant-related immunosuppressive drugs (e.g. cyclosporine, tacrolimus, sirolimus, MMF)
Which 2 organisms are asplenic individuals at increased risk of contracting?
Which vaccine preventable organisms?
Which 3 viruses is an immunocompromised individual at highest risk of contracting?
- Salmonella
- Capnocytophaga
- (also malaria)
Vaccine preventable:
- Strep pneumo (PCV13, PPV23)
- Neisseria meningitidis (Menactra ACYW, Bexsero Men B)
- H. influenza
Viruses
- Adenovirus
- RSV
- Influenza
What is the general work up for Immunodeficiencies?
General screening lab work for immune deficiency:
- CBC with differential –> To evaluate for quantitative deficiency (ex. Lymphopenia, etc)
- Lymphocyte subsets
- CD3 T cells
- CD4 T cells
- CD8 T cells
- B cells
- NK Cells
- Immunoglobulin levels
- IgG, IgA, IgM, IgE
- Vaccination response:
- Tetanus, diphtheria, pneumococcal
- CH50 –> For complement disorders
- Neutrophil Oxidative Burst Index (NOBI) or Nitroblue test –> for CGD
- C1 esterase inhibitor –> for Hereditary angioedema
What are the categories of Immunodeficiencies? Give examples.
How do they present?
What type of immune deficiency presents with recurrent lymphadenitis, bacterial abscesses, recurrent osteomyelitis (usually staph aureus), and Crohn’s like illness?
Chronic Granulomatous Disease
- Phagocytic defect (neutrophils can’t breakdown catalase-positive organisms)
- X-linked recessive
- Diagnosis: Nitroblue tetrazolium dye test, dihydrohodamine test
- Treatment (IgG, abscess drainage and HSCT = definitive)
What type of immunodeficiency presents with angioedema, recurrent pyogenic infections with encapsulated organisms (esp Neisseria), autoimmune disease (ie. SLE) and chronic nephritis?
Complement deficiencies
- Classical complement deficiencies = Presents with recurrent infections with encapsulated infections
- Terminal complement deficiencies = recurrent systemic infections with Neisseria gonorrhea or meningitides
- autoimmune manifestations like lupus or atypical HUS
- angioedema (specific to C1 esterase inhibitor deficiency)
Diagnosis = CH50 to assess classical complement pathway
- C1 esterase if angioedema
Treatment = vaccination, can replace specific complement (ie. recombinant C1 esterase, FFP), HSCT
What is the presentation for CVID?
CVID (Common Variable Immunodeficiency)
- Defect in humoral deficiency due to multiple genetic causes
- Clinical Presentation
- Recurrent sinopulmonary infections with variable onset (>2 years old)
- Gastrointestinal (GI) symptoms:
- Diarrhea, malabsorption, steatorrhea, protein-losing enteropathy
- Giardia infection
- Bacterial overgrowth
- Increased risk of autoimmune disorders (e.g., rheumatoid arthritis)
- Some may present with malignancies (e.g., lymphoma) without having frequent infections
- Diagnosis and Evaluation
- Low IgG and either low IgA or low IgM
- Normal lymphocyte subsets
- Poor responses to vaccines
- Low anti-pneumococcal titres
- Low anti-tetanus/diphtheria titres
- Treatment
- Immunoglobulin replacement therapy
- Immunosuppressive medications if autoimmune manifestations are present
What are clinical findings of acute GVHD?
Within 3 months of transplant
Skin (rash), GI (anorexia, D&V), liver (transaminitis, hyperbili)
Prevent with immunosuppression (cyclosporine, tacrolimus), treat with steroids
What are clinical findings of chronic GVHD?
Occurs more then 3 months post transplant
Skin (malar rash, sica syndrome), MSK (arthritis, joint contractures), lung (bronchiolitis obliterans), liver (cholestasis, bile duct degeneration), eyes (dry eyes, conjunctivitis)
- An 18 month old boy has had 3 pneumonias, 2 episodes of OM and now presents with purulent nasal
discharge. On examination he has a tender 1x1.5cm cervical node with overlying redness. His mother
states that he had an episode of varicella a month ago that was fairly typical in course. Which of the
following investigations will most likely lead to the diagnosis:
Concept: findings of primary immune deficiency
c. Immunoglobulins
PID: recurrent sinopulmonary infections suspicious for innate issues (complement defect), adaptive immunity (B cell defect).
Ix: B cells: look at immunoglobulins and antibody titres
- complement (C3, C4, CH50)
ALSO, CVID and ataxia-telangiectasia both present with recurrent sinopulmonary infections and low immunoglobulins
- Which allergy can be treated with immunotherapy:
b) bee sting allergy
Allergies that respond to immunotherapy:
- seasonal or perennial allergic rhinoconjunctivitis
- asthma triggered by allergen exposures
- insect venom sensitivity
- IVIG can be used in all of the following EXCEPT:
c) nephrotic syndrome
Can be used in: ITP, bone marrow transplant (patients exposed to measles), KD, Guillain-Barre
- A child has received IVIG in the course of their treatment. How long should you wait before giving
them vaccines to ensure adequate response:
d. 11 mo
Varies between 3-11 months depending on product and dose used
- Which is true regarding RAST:
Concept: comparison of RAST to skin testing
d. false positives in children with hyper-IgE states
RAST = testing for allergen specific IgE (now more commonly called allergy specific IgE or sIgE test)
some facts: less sensitive than skin testing, not preferred method for food allergies (skin testing is), BUT not affected by corticosteroids or antihistamines, while skin testing is (neither are affected by montelukast)
13mo child with diaper rash and diarrhea with the introduction of new foods over the
past couple months. Which of the following is most consistent with this presentation:
c. carbohydrate intolerance is a common cause
- Sucrase-Isomaltase Deficiency- high amongst Canadian natives- when feeding milk and lactose- no symptoms- once exposed to sucrose and starches (juice, fruits,
crackers, other starches) develop diarrhea, diaper rash, FTT, abdominal distensionavoid
sucrose and maltose- Rx sacrosidase (Sucraid) - no role for RAST in diagnosis because this is only good for suspected IgE mediated CMPI
- 5 year old had a severe reaction to peanut at 1 year of age. He also has asthma. Now, allergist has
ordered an IgE level for peanut. Mom is wondering why. What do you tell them?
d. it prevents systemic reactions that could result from the skin test
Kid to have RAST for possible peanut allergy: 2 advantages over skin test; 1 disadvantage compared to
skin test.
advantages:
● Better safety
● Results are not influenced by skin disease or medications
disadvantages:
● less sensitive
- Recurrent meningococcal meningitis. Most common immunodeficiency is:
a. C5 deficiency
Consider complement deficiency if:
o Recurrent angioedema
o Autoimmune disease (SLE, nephritis, HUS, partial lipdystrophy) - C1, C3, C4
o Recurrent pyogenic infections
o Disseminated meningococcal or gonococcal infection - C5-9
o 2 episodes of bacteremia - C2
o Meningitis with uncommon serotype (other than A, B or C)
- You suspect a 6 year old of having a T-cell defect. The best screen is:
c. Candida skin test
Screening tests for T cell defect: lymphocyte count, CXR for thymus size, delayed skin tests (candida, tetanus toxoid)
- Deficiency of which of the following may lead to anaphylaxis in a patient given IVIG:
a. IgA
44% have antibodies to IgA (which if they are IgE mediated can cause anaphylaxis to blood products including IVIG)
- In which condition is the IgE level normal, low or high?
Normal:
- immune thrombocytopenic purpura
Low:
- selective IgA deficiency
High:
- Wiskott-Aldrich
- Kawasaki
- A 6 year old presents with eczema, decreased platelets and recurrent OM and
pneumonias. Increased IgA and IgE. Decreased IgG. Your diagnosis is:
a. Wiskott-Aldrich
It’s a TIE! (TCP, immunodeficiency, eczema)
- Low T cell percentages
- treat with IVIG, killed vaccines, BMT curative
Mnemonic: IgG&M low, IgA&E high - it’s a tie
- 3 year old with a history of fevers. Occur every 4 to 12 weeks for 1-4 days. Growing well. Treated for
numerous otitis and pharyngitis.
A) multiple viral infections
- A 15-year-old boy has had 5 episodes of documented pneumonia, 3 RML, 1 RLL, and 1 LLL.
What investigation would be most helpful:
a) immunoglobulins with IgG subclasses
X-linked agammaglobulinemia versus CVID: first have small or no tonsils and lymph nodes, second have normal tonsils and nodes