Allergy & Immunology Flashcards

1
Q

What are contraindications to vaccines?

A
  1. Anaphylaxis to a vaccine component
  2. Severe asthma and LAIV
  3. Intussusception and rotavirus
  4. Hx of GBS within 6wk of vacation
  5. Immunocompromised persons and live vaccines (including those with strong suspicion of immunodeficiency in their families)
  6. Immunosuppressive therapy
  7. Pregnancy and live vaccines
  8. Active TB and MMR /MMRV/Varicella (live vaccines)
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2
Q

What are five types of B cell (humoral) immunodeficiency?

A
  1. X-linked agammaglobulinemia (onset w/in 2y with recurrent sinopulmonary infections and abscent lymph nodes and tonsils)
  2. Common variable immune deficiency (CVID) - (onset >10y with Sinupulmonary infections, autoimmune, granulomatous disease, GI issues, malignancy)
  3. Selective IgA deficiency
  4. Specific antibody deficiency
  5. IgG subclass deficiency
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3
Q

What are the 10 warning signs of primary immunodeficiency?

A
  1. 4+AOM in 1y
  2. 2+ serious sinus infection in 1y
  3. 2+ pneumonias in 1y
  4. 2+ months of ABx with little effect
  5. 2+ deep-seated infections including septicemia
  6. FTT
  7. Recurrent, deep skin or organ abscesses
  8. Persistent thrush in mouth or fungal infection on skin
  9. Need for IV ABx to clear infections
  10. FHx of history of PI

Others:

  1. Autoimmunity (cytopenias, endocrinopathies, GI disturbance)
  2. Difficult to treat dermatitis despite treatment adherence
  3. EBV-associated malignancies
  4. A severe infection (e.g. invasive pneumococcal infection - 25% will have primary immunodeficiency)
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4
Q

What is the differential for immunodeficiency?

A
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5
Q

What investigations should you order if you suspect a humoral immunity defect?

A

Humoral Immunity:
• CBC and differential
• Serum immunoglobulins (how do you order this?)
• Serum specific antibody titres (diptheria, tetanus, can consider pneumococcal, MMR)

• Flow cytometry to identify B-cell markers and numbers

Advanced humoral testing:
• Flow cytometry to determine B-cell subsets (i.e. naïve vs switched memory)

• In vitro immunoglobulin production to mitogens

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6
Q

What investigations should you order if you suspect a T-cell immunity defect?

A

T-cell defects
• Newborn Screening
• CBC and differential
• Flow cytometry (CD4, CD8, NK cells)
• In vitro proliferation to mitogens (i.e. pokeweed, concanavalin A)

• Cutaneous delayed hypersensitivity

Advanced T-cell tests
• T-cell subset analysis (naïve, memory, activated)

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7
Q

What investigations should you order if you suspect a Phagocytic defect?

A
  • CBC and differential
  • Dihydrorhodamine testing (or NBT)
  • Flow cytometry for adhesion molecules
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8
Q

What investigations should you order if you suspect a Complement defect?

A
  • CH50 assay (classical complement pathway)
  • AH50 assay (alternative complement pathway) • MBL (mannose binding lectin pathway)
  • C3/C4
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9
Q

What pathogens are most associated with chronic granulomatous disorder?

A
  • Pathogens: Catalase positive (staph, aspergillus, nocardia, serratia marcescens, burkholderia cepacia, salmonella)
  • Infections: Recurrent bacterial and fungal infections - things like adenitis, empyema/PNA, abscess, OM, sepsis, granulomas
  • Can have IBD
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10
Q

What are the clinical features of Hyper IgE Syndrome?

A
  1. Recurrent abscesses in lung, skin - these present as “cold boils” because they’re not your usual hot tender abscesses. Caused by staph and can have pneumatoceles.
  2. Can have mucocutaneous candidiasis
  3. Eczema, papulopustular lesions
  4. Facial features - deep set eyes, prominent forehead, broad nasal bridge, bulbous nose, coarse skin
  5. Delayed shedding of teeth and fractures!
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11
Q

What are the different treatments for CGD, HyperIgG and LAD?

A
  1. CGD - abx (TMP-SMC), and itraconazole (fluco not good for aspergillus), anti-inflammatories
  2. HyperIgG - anti-staph prophylaxis with Septra
  3. LAD - abx, HSCT
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12
Q

What are the clinical features of X-linked agammaglobulinemia?

A
  • Present with recurrent bacterial sinopulmonary infections
  • Typically start in the first 2 years of life
  • Most common infectious organisms – Streptococcus pneumoniae, Haemophilus influezae
  • Other microorgansms of concern – ECHO virus, Helicobacter, Campylobacter, Pseudomonas, Ureaplasma, Mycoplasma
  • Absence of LN on exam!
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13
Q

What is the management of X-linked aggamaglobulinemia?

A
  • Repalcement immunoglobulins
  • Antimicrobial prophylaxis
  • Recurrent monitoring of pulmonary status - These patients are at risk of bronchiectasia
  • Consider lung transplant in patients with agammaglobulinemia and life-threatening chronic lung disease
  • Can present with enteroviral meningitis – requires treatment with IV Ig
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14
Q

What is the definition of CVID (note: universal definition does not exist)

A
  1. Low IgG and low IgA/M with poor response to vaccines
  2. Exclude other causes of humoral immunodeficiency (note: B cells can be normal)
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15
Q

What is the triad of Wiskott-Aldrich Syndrome?

A
  1. Eczema
  2. Thrombocytopenia (uniformly small platelets)
  3. Recurrent infections (sinopulmonary and viral)
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16
Q

Why might a baby have no thymus?

A

Immunodeficiency (E.g. SCID, Di George), sepsis, cardiac surgery, RDS, steroid exposure

17
Q

What are the clinical manifestations of HyperIgE syndrome?

A

Skin:

  • Eosinophilic pustules as newborn
  • Eczematoid dermatitis (but no allergies, asthma) • Autosomal recessive forms will have allergies
  • COLD ABSCESSES – no redness, warmth, or pain

Infections
• Frequent sinopulmonary (S. aureus, S. pneumoniae)

  • Pneumatocele formation
  • Opportunistic infections
  • Mucocutaneous candidiasis
  • Afebrile, will feel well
18
Q

What syndrome do each of the following clinical scenarios indicate?

  1. Hypocalcemia, unusual facies and ears, congenital heart disease
  2. Delayed umbilical cord detachment, leukocytosis, recurrent infections
  3. Persistent thrush, FTT, pneumonia, diarrhea
  4. Bloody stools, draining ears, atopic eczema, thrombocytopenia
  5. Pneumocystis jiroveci pneumonia, neutropenia, recurrent infections
A
  1. Di George
  2. Leukocyte adhesion deficiency (LAD)
  3. SCID
  4. Wiskott-Aldrich
  5. X-linked Hyper-IgM syndrome
19
Q

What syndrome do each of the following prompts indicate?

  1. Severe progressive infectious mononucleosis
  2. Recurrent staphylococcal abscesses, staphylococcal pneumonia with pneumatocele formation, coarse facial features, pruritic dermatitis
  3. Persistent thrush, nail dystrophy, endocrinopathies
  4. Short stature, fine fair, severe varicella
  5. Oculocutaneous albinism, recurrent infection
  6. Abscesses, suppurative lymphadenopathy, antral outlet obstruction, pneumonia, osteomyelitis
A
  1. X-linked Lymphoproliferative
  2. Hyper-IgE syndrome
  3. Chronic mucocutaneous candidiasis
  4. Cartilage hair hypoplasia and short-limbed dwarfism
  5. Chediak-Higashi syndrome
  6. Chronic granulomatous syndrome
20
Q

What syndrome do the following prompts indicate?

  1. Progressive dermatomyositis with chronic enterovirus encephalitis
  2. Sinopulmonary infections, neurologic deterioration and telangiectasia
  3. Recurrent Neisseria Meningitis
  4. Sinopulmonary infections, splenomegaly, malabsorption
A
  1. X-linked agammaglobulinemia
  2. Ataxia-telangiectasia
  3. C6, C7, or C8 deficiency
  4. Common variable immunodeficiency
21
Q

Match the key word or clue with the type of inborn error of immunity:

  1. Herpes virus
  2. EBV
  3. Enterovirus
  4. Pneumococcus
  5. Neisseria meningitidis
  6. Staphylococcus abscesses
  7. Serratia
  8. Atypical mycobacteria
  9. PJP, cryptococcus
A
  1. Innate, T cells
  2. X-linked lymphoproliferative disease, NK cell defects
  3. Innate, humoral
  4. Innate, humoral, complement
  5. Complement
  6. CGD, Hyper-IgE
  7. CGD
  8. INF-gamma pathway, T cells
  9. T cells
22
Q

For T cell, B cell, Phagocytic, and complement defects, list the following:

  1. Age of onset
  2. Typical bacteria
  3. Typical viruses
  4. Typical fungi/parasites
  5. Sites of infections
  6. Associated features
A
23
Q

What is your differential for IEI with the absence of lymph tissue?

A
  1. Agammaglobulinemia - e.g. XLA
  2. SCID
24
Q

What is your differential for IEI with lymphadenopathy?

A
  • CVID (common but not always present)
  • autoimmune lymphoproliferative syndrome
  • X-linked lymphoproliferative syndrome
  • Omenn syndrome
  • CGD
  • HLH
  • Consider: infection, malignancy, inflammation, autoimmunity
25
Q

After giving the following doses of IVIG, how long should you wait to give a live vaccine (e.g. MMR)?

A
  • If 300–400mg/kg IV given → wait 8 months
  • If 1g/kg IV given → wait 10 months
  • If 2g/kg IV given → wait 11 months
26
Q

What are the differences between serum sickness and serum sickness-like syndrome?

A
  • Serum sickness
    • Onset: 1-3 weeks of drug exposure
    • Sx: Rash, arthralgias/arthritis
    • ATG (anti-thymocyte globulin), monoclonal antibodies
    • Ix: low complement
    • Management: Stop meds, NSAIDS, analgesics, steroids, plasmapheresis for severe cases
  • Serum sickness-like
    • Onset: 1-3 weeks of drug exposure
    • Rash, arthralgia/arthritis, fever
    • Sx: Rash (can look urticarial, typically less migratory or morbilliform), arthralgia/arthritis, lymphadenopathy & edema, NO renal disease, fever, NO mucous membrane involvement
    • Normal complement, reasonable to check liver/kidney function
    • Common trigger: penicillin, cefaxlor
    • Management: stop medication (do not rechallenge), NSAIDS, analgesics
27
Q

What are the advantages and disadvantages of skin prick testing for food allergies?

A
  • Advantages: results within 15min, more sensitive to serum specific IgE, high NPV, cost effective
  • Disadvantage: False positives (up to 50%), affected by use of antihistamines or corticosteroids, risk of systemic reaction, cannot perform if skin disease (e.g. eczema)
28
Q

What are the advantages and disadvantages of serum specific IgE/RAST testing for food allergies?

A
  • Advantages: not affected by meds, no risk of a systemic reaction, can be performed if skin disease is present
  • Disadvantages: false positives if elevated total IgE, less sensitive compared to SPT, more expensive than SPT