what are some condition with high total IgE?
Immunodeficinecy plus increased total IgE?
what is the 1/2 life of IgE?
2 days
Does IgE cross the
... [Show More] placenta?
no
reaches a peak between 10 and 15 years of age
what conditions have decreased IgE?
recurrent sinopulmonary infections, HTLV-1 infections, primary biliary cirrohsis
KEY FACT:
Polymorphisms of CCL11 (eotxain) are associated with serum total IgE; increased in blacks, decreased in whites
what are early phase mediators?
late phase?
what factors affect skin tests:
age?
device?
chronic conditions
meds?
how long should patients stop H1 blockers? H2 Blockers? nasal antihistamines?
1-3 days
7 days
2 days
what are some reasons for false-positive and false negative skin tests?
Sensitivity and specificity of SPT for inhalant allergy:
for food allergy:
80-85%
30-70%--high rates of false positives.
skin testing to fresh fruits and veggies increases sensitivity to 90%
relative contraindications to SPT?
poorly controlled asthma
severe reactions to minute amounts of allergen
ID skin tests should be performed with what dilution?
100-to-1000 fold dilution
0.02-0.1 ml of allergen with 26 or 27 gauge needle
do SPT before
compared to SPT, are IDST more sensitive or specific?
more reproducible and sensitive
less specific (high false-positive rate)
any reaction larger than the negative control may indicate the presence of specific IgE antibody--though small positive reactions may not be clinically significant
For venom hypersensitivity: testing done up to ___microgram/ml?
1 microgam/ml.
false positive rates increase above this concentration
IDST's are especially imp for diagnosing venom hypersensitivity as failure to identify can lead to life-threatening consequences
regarding inhalant allergies, when is IDST most helpful
weaker nonstandardized inhalant allergens
less helpful for cat or grass
is ID testing ever used for Food or latex allergy?
no, high rate of systemic reactions
Key Fact:
Venom ID skin tests are performed up to 1 mcg/ml. Do not include any positive flying hymenoptera skin tests at 10 mcg/ml in venom IT prescriptions as this concentration is kinown to be directly irritating to the skin
what are advantages and disadvantages of delayed-type hypersensitivity testing?
DTH results from the activation of specific T cells by?
antigen-presenting langerhans cells in the skin
T cell activation leads to cellular infiltration with macrophages, monocytes and lymphocyte in a nonspecific fashion.
These cells secrete TNFalpha, IFN gamma and other inflammatory cytokines.
histamine and serotonin release results in increased vascular permeability
Key fact:
A positive DTH test reflects prior exposure to the antigen in question and is typically reassuring if the DTH is being done to assess competence of cellular immunity.
A negative DRH? test may simply reflect lack of exposure to the antigen or it may reflect anergy as a result of either primary or secondary cellular immunodeficiency
what are drugs that inhibit the nasal response and washout periods?
stimulus:
cold and dry air:
hyperosmolar solution
capsaicin
air pollutants and other irritants
cold and dry air--symptoms associated with sensorineural activation and mast cell mediator release
hyperosmolar solution -- either NaCl or mannitol activate mast cells in a nonantigenic fashion
capsaicin - acts on the vanniloid receptor TRPV1 located on unmyelinated, slow-conducting sensory nerve fiber
air pollutants and other irritants - tobacco, volatile organic compounds, perfrume, cleaning products
biochemical stimuli:
histamine
methacholine
adenosine
neuropeptide
what are contraindications to nasal provocation?
what does spirometry actually measure?
airflow obstruction and lung restriction
what is the most reproducible pulmonary function test?
what is the primary outcome measure in most FDA phase 3 asthma drug trials
FEV1
how are lung volumes measures?
body plethysmography
What things increase DLCO
what things decrease DLCO?
increase -- exercise, suping, L to R shunt
decrease -- COPD/emphysema, bronchiolitis, and ILD
asthmatics may have normal or high DLCO
what age can you do spirometry.
usually age 6 and up
how to interpret a PFT?
1) effort ---exhale for at least 6 seconds in adults, 3 seconds in kids
2) reporoducible -- 3 efforts within 150 ml of each other
3) look at flow-volume loop.
what does vocal cord dysfunction (variable extrathoracic obstruction) look like?
what does fixed upper airway obstruction
what does variable intrathoracic obstruction look like?
what is an example
tracheomalacia
Key Fact:
A significant response to bronchodilator in adults is an increase in FEV1 of 12% and > 200 ml
Algorithim for interpreting PFT's
Key fact:
Severity of airway hyperresponsiveness (AHR) does not correlate with severity of asthma
Key Fact:
Nonselective or nonallergic vs selective or allergic agents: Nonselective agents have the potential to produce bronchoconstriction in all asthmatics, and they do not purge any specific triggers. Selective testing [Show Less]