Allergy and Immunology Flashcards
Signs of impaired phagocytes?
Chronic or early infections of the skin, mucous membranes, lungs, bone or liver.
10 warning signs for immunodeficiency
- 4 or more new ear infections in 1 year
- 2 or more serious sinus infections within 1 year
- 2 or more months on antibiotics with little effect
- 2 or more pneumonias within 1 year
- Failure of an infant to gain weight/grow normally
- Recurrent, deep skin or organ abscesses
- Persistent thrush in mouth or skin fungal infection
- IV abx needed to clear infections
- 2 or more deep seated infections including septicemia
- FmHx of primary immunodeficiency
Risk factors for allergic rhinitis (6)
- FmHx of atopy
- mothers who smoke heavily
- serum IgE >100 IU/mL before age 6
- heavy exposure to indoor allergens
- C/S delivery
- 2 or more episodes of rhinorrhea in the first year of life
What can be done to reduce the risk of developing allergic rhinitis?
- exposure to cat/dog dander early in childhood
- prolonged breastfeeding
- early introduction to wheat, rye, oats, barley, fish, eggs
What are some complications of allergic rhinitis?
- chronic sinusitis
- persistent cough
- eustachian tube obstruction and middle ear effusion
- tonsillar/adenoid hypertrophy
- OSA
- daytime fatigue
What are the diagnostic criteria for anaphylactic shock?
- acute onset of illness with involvement of the skin and/or mucous membranes along with either a) respiratory compromise or b) reduced BP or signs of end-organ dysfunction
- 2 or more of the following signs rapidly following exposure to a likely allergen: skin/mucosal involvement, respiratory compromise, reduced BP, persistent GI symptoms
- reduced BP after exposure to a known allergen
What advice should be given to a child with numbness and tingling after oral ingestion of apples or plums?
- advise the child that they likely have oral allergy syndrome
- will need further testing for confirmation
- may be able to tolerate cooked or processed forms of that food, but should carry and EpiPen and avoid completely if systemic reaction occurs
What is the dose of Epinephrine that must be given in the event of anaphylactic shock?
Epinephrine 1:1000 0.01 mg/kg IM into anterolateral thigh
Mother brings her 6 month old baby boy to your office. He has had two episodes of AOM since birth. He also has eczema and some bloody stool. He also had prolonged bleeding after his circumcision. What is the likely diagnosis?
Wiskott-Aldrich Syndrome (X-linked recessive)
What is the curative treatment for WAS?
bone marrow or cord blood transplantation
Recurrent/multiple skin/lung/bone/GU infections with aspergillus, staph aureus, serratia and salmonella is concerning for what condition?
Chronic granulomatous disease
What test should be done to diagnose Chronic granulomatous disease?
- NiroBlue Tetrazolium test
- neutrophil oxidative burst index
What steps should be taken to treat children with CGD?
- antibacterial and antifungal prophylaxis
- aggressive treatment of infections when present
- bone marrow transplantation
What are the distinguishing features of Job’s Syndrome?
- cold abscesses in the skin/lungs
- coarse facies
- high Ig E count and eosinophilia
- poor antibody response to vaccines
- delayed shedding of teeth
- eczema
What condition should be considered in the event of delayed cord separation? What other features are present?
Leukocyte adhesion defect
will also see:
- lack of pus (as neutrophils are unable to leave blood vessel lumen)
- large chronic ulcers
Which immunologic condition is associated with partial oculocutaneous albinism?
Chediak-Higashi
Rare, AR condition
Defective neutrophils, mild bleeding diathesis, partial oculocutaneous albinism, progressive peripheral neuropathy, development to HLH
What clinical features are seen in cases of hereditary angioedema?
- Episodic attacks of non-pitting, non-puritic edemic in the absence of urticaria
- May see a prodrome of tightness/tingling the area that will swell
- May see erythema marginatum (flat erythema)
- Abdominal pain that does not occur at the same time as peripheral edema
- Absent response to epinephrine, antihistamines, glucocorticoids
- Worsened by ACEi and estrogen (menstruation)
What treatment can be offered for HAE?
Long-term prophylaxis or treatment of acute attacks with purified C1-INH (Cinryze, Berinert)
Androgens
How do you distinguish serum sickness from serum sickness-like reactions?
- SSL are more likely to be triggered by medication/drugs
- because there are no immune complexes, these patients should have normal complement levels, no vasculitis and no renal complications (no proteinuria or lymphadenopathy)
What is the management approach to serum sickness/serum sicknesss-like reactions?
No evidence based guidelines; generally supportive
- discontinue offending agent
- NSAIDs, antihistamines
- may use systemic steroids for severe cases (i.e. prednisone)
What condition presents with complete absence of lymphoid tissue?
Bruton’s X-linked agammaglobulinemia
- complete absence of B cell lymphocytes, IgG, IgA, IgM, antibodies ot vaccines
- absent lymph nodes and tonsils
- history of recurrent sinopulmonary infections, otitis media, GI infections, meningitis (enteroviral), sepsis
Management for X-linked agammaglobulinemia
- Immunoglobulin G replacement (monthly or weekly)
- genetic confirmation of BTK mutation and counselling for family
- PFT and CT scan looking for bronchiectasis
- prompt antibiotic treatment for suspected infections
What is the most common humoral deficiency condition?
Selective IgA deficiency (which later can become Common variable immunodeficiency (AD), peaking usually in adulthood)
What clinical features are seen in CVID?
- presence of lymphoid tissue
- 20-25% risk of autoimmune conditions i.e. IBD, gastritis, arthritis, alopecia areata, granulomas, small bowel nodular lymphoid hyperplasia
- increased risk of all malignancies
What considerations are required for a child with selective IgA deficiency with respect to blood products?
- Cannot receive IV Ig (can cause anaphylactic reaction due to IgE antibodies that can develop against IgA antibodies)
- Can receive blood products from IgA deficient individuals and washed pRBCs/platelets
What other conditions are IgA deficient individuals at risk for?
- autoimmune diseases: RH, SLE, Sjogren syndrome, insulin dependent DM, pernicious anemia, IBD, autoimmune hepatitis
- celiac disease
- malignancy
What features on history would raise suspicion for a complement deficiency?
- Recurrent extragenital infection with gonorrhea
- Recurrent infection with neisseria meningitis or other encapsulated bacteria
- autoimmune conditions (SLE-like) without typical serology i.e. normal ANA
What investigations should be done to assess complement function?
- CH50 - for total number (note, C3/C4 will usually be normal and thus not useful)
- alternative pathway (AH50)
How should a child with suspected complement deficiency be managed?
- Immunizations for pneumococcal and meningococcal bacteria
- Antibiotic prophylaxis
What laboratory findings are common in the case of Wiskott-Aldrich Syndrome?
Elevated IgA and IgE
Low IgM
Absent/low isohemagglutinins
What are the benefits of RAST testing (serum specific IgE testing) over skin prick testing?
- not affected by antihistamines, corticosteroids, montelukast
- no risk of systemic reaction
- can be performed if there is skin pathology i.e. eczema
What are the benefits of skin prick testing over RAST testing?
- fast (results within 15 minutes)
- less invasive
- cheap
- more sensitive
What are the pitfalls of Serum Specific IgE testing?
- if there is elevated total IgE, can have false positives
- expensive
- less sensitive
What are the disadvantages of skin prick testing?
- theoretical risk of systemic reaction
- false positives (as high as 50%)
- affected by use of antihistamines, steroids or montelukast
- cannot perform if skin is not in good condition
