Download Diagnostic Techniques

Diagnostic Techniques for
Inhalant/Environmental
Treatment
George F. Kroker, MD FACAAI
Tools of the Allergist--Inhalants
 Skin Tests
 Scratch
 Skin
Prick Test
 Intradermal (ID, IDT)
 In Vitro Tests
 Specific
IgE
RAST (radioallergosorbent test)
 ELISA (enzyme-linked immunosorbent assay)

 Total
IgE, other immunological tests
Copyright 2015 Allergy Associates of La Crosse
Test Preferences—Vary by
Specialty
 Board Certified Allergist
 Skin
Prick Test (SPT)
 Intradermal Test (ID)
 In Vitro Specific IgE
 ENT Allergist
 Intradermal
Dilutional Test (IDT)
 Modified Quantitative Test (MQT)
 In Vitro Specific IgE
Copyright 2015 Allergy Associates of La Crosse
Annals of Allergy
101:580-592, 2008
Copyright 2015 Allergy Associates of La Crosse
The Importance of the History
 “The clinical history drives the
diagnosis of human allergic
disease…the clinical history makes the
critical link between the allergy skin or
blood test results and the allergic
disease”
Pearls and pitfalls of allergy diagnostic testing: report from the
ACAAI/AAAAI Specific IgE Test Task Force. Annals of Allergy,
Asthama and Immunology. Dec 2008;101:580-592.
Copyright 2015 Allergy Associates of La Crosse
The Importance of History
(cont.)
 “Diagnostic tests should be used to support
or exclude a diagnosis of specific allergies
based on the history. They should almost
never be used as a substitute for a careful
history…neither skin tests nor serum IgE
tests should be either requested or
interpreted outside the context of the clinical
history and physical examination…”
Pearls and pitfalls of allergy diagnostic testing: report from the
ACAAI/AAAAI Specific IgE Test Task Force. Annals of Allergy,
Asthama and Immunology. Dec 2008;101:580-592.
Copyright 2015 Allergy Associates of La Crosse
The La Crosse Method
Perspective
 We recognize that various allergy testing


techniques have their rightful place
Our ultimate goal is to deliver SLIT
treatment at the optimum therapeutic
level in a streamlined manner
Our testing protocols have been
developed to provide a high degree of
quantification of the patient’s
sensitivities as efficiently as possible
Copyright 2015 Allergy Associates of La Crosse
Where are we now?
 Optimized IDT: streamlined to reduce
patient’s time in the office
 Selective use of In Vitro testing
 Determine which specific SLIT protocol
is best suited for the patient
 Treat at the therapeutic dose
 Retest allergens being treated to
monitor effectiveness of current dose
Copyright 2015 Allergy Associates of La Crosse
How did we get here?
Brief review of skin testing techniques
 History of skin testing techniques
 Types of techniques
 Principles applicable to all techniques
 Advantages & disadvantages of each
technique
Copyright 2015 Allergy Associates of La Crosse
History of the Skin Test
Charles Blackley, MD
1820-1900
Copyright 2015 Allergy Associates of La Crosse
Daily Pollen Counts
May 28-Aug 1, 1866
Types of Skin Tests
 Epicutaneous
 Scratch
 Prick-puncture
 Modified
prick
 Intradermal
 Single
strength
 Intradermal
Dilutional Titration
(IDT)
Copyright 2015 Allergy Associates of La Crosse
Skin Testing: A Common Goal
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Factors influencing skin test
reactivity
 Age: Reactivity progressively increases



throughout childhood to about age 20-30,
then gradually declines until age 50, after
which the decline is more rapid
Menstrual cycle: Reactions to allergen &
histamine larger at midcycle
Seasonal: Reactions to a seasonal allergen
are greater just after the allergy season is
finished
Sun Damage: Affects skin mast cell
number
Copyright 2015 Allergy Associates of La Crosse
Factors influencing skin test
reactivity
 Site tested: Upper back > lower back>
forearm
 Clinical status on day of testing:
Heavy allergen exposure immediately
before testing can enhance reactivity
 Other diseases: cancer, etc.
 Medications: Antihistamines, tricyclic
antidepressants, H2 antagonists reduce
reactivity
Copyright 2015 Allergy Associates of La Crosse
Wait time for testing after
med d/c
First-generation H1
meds
Second-generation
H1
>24 hrs
(hydroxyzine 72 hrs)
>72 hrs
H2 blockers
<24 hrs
Tricyclic
antidepressants
>7-14 days
Copyright 2015 Allergy Associates of La Crosse
Epicutaneous: Scratch Test
 Method: Knife blade or allergen abrades an area of
skin in linear fashion, producing a superficial scratch.
Allergen extract applied.
 Advantage:
 Time
 Safety
 Disadvantage:
 Lack of uniformity of abrasion
 Uncomfortable & traumatic
 Increased false pos & false neg compared to
prick/puncture
Copyright 2015 Allergy Associates of La Crosse
Epicutaneous: Puncture Test
 Method:
 Drop
of extract is placed on
the skin
 Testing device (lancet,
bifurcated needle) placed
perpendicular
to the skin
 Device is tapped gently
through the drop of extract,
and held on the skin with
pressure for about 1second
Copyright 2015 Allergy Associates of La Crosse
Epicutaneous: Modified Prick
Test
 Method:



Drop of extract placed
on skin
Needle is introduced
laterally into skin at an
angle, through the drop
Skin is lifted up with no
downward pressure
introducing a minute
amount of extract into
the skin
Copyright 2015 Allergy Associates of La Crosse
Stand-Alone Skin Prick Tests
 Stand-alone SPT favored by many allergists



for its specificity, safety, and efficiency
Reactions are graded based on wheal size,
presence of pseudopods, and in comparison
to pos/neg controls
Results graded from 1+ to 4+
Multi-prong device may be used to speed
application and provide consistency
Copyright 2015 Allergy Associates of La Crosse
Intradermal: Single-strength
 “The value of prick tests is limited by
low potency extracts producing false
negative results.”
 “Infrequently, an intradermal test will
reveal a clinically relevant reaction in
the case of a negative prick test.”
Allergy: Principles & Practice, 5th ed 1998
E. Middleton Ed.
Copyright 2015 Allergy Associates of La Crosse
Intradermal: Single-strength
 “Intracutaneous testing may be useful
and should be pursued if the
prick/puncture test is negative or
equivocal to allergens strongly
suggested by the patient’s history or
exposure.”
Joint Task Force on Practice Parameters for the Diagnosis and Treatment
of Asthma. Annals of Allergy, Asthma and Immunology. 1995;75: 543-625.
Copyright 2015 Allergy Associates of La Crosse
Intradermal: Single-strength
 Method: Testing performed with disposable
tuberculin syringe and small gauge needle
 A small amount (.02ml) of dilute extract is
injected into the superficial layers of the
skin, making wheals approximately the
same size
Copyright 2015 Allergy Associates of La Crosse
Intradermal: Single-strength
 Advantage
 More
sensitive than prick test
 Disadvantage
 Less
specific than prick test
 Rate of systemic reactions, <0.5%
 Can cause large local reactions
 First fatality reported 1922 fish ID injection
Copyright 2015 Allergy Associates of La Crosse
Epicutaneous Skin Testing
“Despite its widespread adoption as the premier
method used in clinical practice, many
characteristics of the skin prick or puncture test are
poorly defined…it is concerning that a standard
protocol for skin prick testing has yet to be
universally adopted. Arcane systems are still being
used to grade skin prick test wheal-and-flare
responses (i.e., grade 1 to 4+) which greatly
impedes communications of results between
different clinics.”
The skin prick test: “more than meets the eye”David
Bernstein M. Annals of
Allergy, Asthma and Immunology. June 2003;92: 587-588. (Editorial)
Copyright 2015 Allergy Associates of La Crosse
Epicutaneous Skin Testing
 What do allergy skin tests really mean?

“Categorization of skin test results from 0 to 4+ is
analogous to recording the results of a CBC and
differential as a moderate white count with 2+
neutrophils, 3+ lymphocytes, and 1+ bands. One
could argue that if we are only concerned about white
blood cell counts that either are very low or very high,
such categorization should be adequate. Even so,
most physicians prefer to review the actual numbers
so they can interpret the results themselves. Why
should we not do the same for skin test results?”
What do allergy skin tests really mean? Portnory, JM. Annals of Allergy,
Asthma and Immunology. 2002 Oct;89(4):335-6.
Copyright 2015 Allergy Associates of La Crosse
History of IDT
 1911: Leonard Noon

injected allergy patients
with pollen extracts (to
induce production of
pollen “antitoxin”)
Attempted to determine
degree of sensitivity of his
pts by making various
dilutions of antigens and
instilling them into the
patient’s conjunctiva
Copyright 2015 Allergy Associates of La Crosse
Leonard Noon MD
1878-1913
History of IDT
 Noon quantified a patient’s sensitivity by instilling

drops of different-strength pollen extracts into the
conjunctiva of a known hay fever patient
The strength of extract required to produce a
minimal reaction would then represent the patient’s
“resistance”: i.e., if a dilution of four “units” was
required to institute a reaction, the patient’s
“resistance” was rated as 4
 These quantified responses could then
be used in selecting the appropriate dose
for injection therapy
Copyright 2015 Allergy Associates of La Crosse
Noon’s Quantified Results
Copyright 2015 Allergy Associates of La Crosse
History of IDT
“Three quarters of a century later, a large percentage of the allergy
world uses basically non-quantitative techniques of diagnosis and
treatment…there is also considerable disagreement regarding an
appropriate starting dose for therapy. It has been observed that
should William Osler be returned to life, he would be unable to
recognize most of the technology in use. If Leonard Noon
returned, he could resume his practice as he left it with little
difficulty. He would probably continue to seek better
quantification.”
Endpoint titration and immunotherapy. King HC. Otolaryngology Clinics of
North America. 1985 Nov;18(4):703-17.
Copyright 2015 Allergy Associates of La Crosse
History of IDT
French K. Hansel MD
1893-1981
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Herbert J. Rinkel MD
1896-1963
History of IDT (cont.)
 1930: French Hansel was the first to



perform skin tests using multiple-strength
individual extracts instead of singleconcentration extracts
He used intradermal injections of antigens in
serial 1:10 ratios of varying strengths
while measuring the response
He demonstrated that each antigen has a
unique response in a given patient
He found the strength of a response to
different antigens is not the same for all
the antigens encountered by a given
individual
Copyright 2015 Allergy Associates of La Crosse
History of IDT (cont.)
 Hansel concluded that multiple intradermal skin
tests using individual allergens with varying
doses produced greater accuracy of
information regarding the degree of the
patient’s sensitivity
 1937: Herbert Rinkel, an allergist working with
Hansel, found that an antigenic dilution ratio
of 1:5 administered in progressively increasing
increments was qualitatively and quantitatively
superior in measuring allergic skin reactivity.
The response was constant through 3 or 4
dilutions in 72% of patients
Copyright 2015 Allergy Associates of La Crosse
Goals of IDT
 Reliably identify an inhalant sensitivity by skin
testing
 Determine a safe starting point at which to
initiate therapy (the “threshold dose”)
 Allow treatment to be started during patient’s
peak allergy season
 Treat a variety of allergens of different degrees of
sensitivity in a single mix by varying the
concentration of individual antigens according to
the skin test reactions (“Multi-antigen threshold
therapy”)
Copyright 2015 Allergy Associates of La Crosse
Principles of IDT
 IDT is based upon the interpretation of the


skin response to the injection of weak
(nonreacting) dilutions of antigen,
proceeding to stronger (reacting) dilutions of
the antigen
The first test producing a wheal 2 mm
larger than the preceding non reacting
wheal is considered the endpoint of the
reaction
Treatment based on the endpoint
response is within a safe and therapeutic
range
Copyright 2015 Allergy Associates of La Crosse
IDT: Standard Technique
 Allergenic extracts are prepared using 5-fold
serial dilutions (Concentrate to a #6)
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LCM Serial Dilutions
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LCM Concentrates & No 1 dil
Copyright 2015 Allergy Associates of La Crosse
IDT: Standard Technique
 The antigen is injected intradermally,


creating a demarcated 4mm wheal
containing approx .01 ml of the appropriate
dilution
The number 6 dilution of each antigen is
administered
The response is measured at 10 min
Copyright 2015 Allergy Associates of La Crosse
IDT: Technique
Copyright 2015 Allergy Associates of La Crosse
IDT: Standard Technique
 The wheal will normally grow to 5mm
within 10 minutes
 If less than 2mm growth, the result is
interpreted as negative and a stronger
dilution is applied
 The first dilution to establish a 7mm
wheal is considered the “endpoint”
 Confirmation: show a clear progression
of wheal size of 2mm over 3
consecutive dilutions
Copyright 2015 Allergy Associates of La Crosse
IDT: Typical Std Titration Results
#6
#5
#4
#3
4
4
5
7
Endpoint
5
5
7
Endpoint
Copyright 2015 Allergy Associates of La Crosse
9
#2
9
#1
IDT: Std Titration
Copyright 2015 Allergy Associates of La Crosse
IDT: Standard Technique
 This process may take several hours
and/or 2 or more sessions depending
on the number of allergens being
tested, the severity of reactions,
abnormal skin or whealing responses,
etc.
Copyright 2015 Allergy Associates of La Crosse
La Crosse Method: Optimized IDT
 Technique of administration of antigens is
identical to standard titration, except for starting
dilution
 In contrast to giving a number 6 starting
dilution for all antigens, varying-strength
starting dilutions are used for different
antigens, based on clinical experience and
the patient’s own history
 Goal: to find 2 mm wheal growth response
(i.e, 7mm wheal in 10 minutes) with further
confirmation by giving additional selected test
dilutions as needed
Copyright 2015 Allergy Associates of La Crosse
Optimized IDT Screening Dilutions
Dog
TCE
Cladosporiu
m
Alternaria
Aspergillus
Penicillium
AA Mold Mix
3
Cat
Fall pollen
3
Oak
Tree
Birch
3
Bermuda
Grass Mix
Ragweed
3
Cockroach
Mite
2
2 2
2
2
2
2
2
2
3
3
3
3
3
3
3
Normal Degree of Clinical Sensitivity
3
4
4
4
4
3
Moderate Degree of Clinical Sensitivity: DROP BACK 1 DILUTION
4
5
5
5
5
4
4
4
4
4
4
High Degree of Clinical Sensitivity DROP BACK 2 DILUTIONS
Copyright 2015 Allergy Associates of La Crosse
4
4
IDT Technique: Advantages of
Optimized vs Standard IDT
testing
 Speeds up testing process
 Minimizes the number of
skin tests & patient’s
discomfort
 Minimizes testing expense
 Allows better workflow so
that more patients can be
tested in the same amount
of time
Copyright 2015 Allergy Associates of La Crosse
Modified Quantitative Testing
(MQT)
 Skin Prick Test (SPT) is first used as a
rapid screening measure of reactivity,
then selective IDT testing done based
on SPT results
 Using the Multi-Test II device is
estimated to yield a skin response
equivalent to a 1:1500 w/v IDT, this first
step is similar to a #3 dilution
Current in vivo and in vitro screens for inhalant allergy. KrouseJH, Stachler RJ, Shah
A. Otolaryngology Clinics of North America. 2003 Oct;36(5):855-68.
Copyright 2015 Allergy Associates of La Crosse
Multi-Test
 Device allows consistent application of
multiple tests to screen initial sensitivity
 Rapid, with minimum patient discomfort
Copyright 2015 Allergy Associates of La Crosse
Modified Quantitative Testing
(MQT)
 SPT is used in combination with IDT
 If
SPT negative, a single stronger IDT may be
administered
 If SPT positive, a single weaker IDT may be
administered
 The combination of SPT with IDT yields an
efficient, rapid estimate of the strength of the
allergic response that can be interpreted and
used in treatment vial preparation
Current in vivo and in vitro screens for inhalant allergy. KrouseJH,
Stachler RJ, Shah A. Otolaryngology Clinics of North America. 2003
Oct;36(5):855-68.
Copyright 2015 Allergy Associates of La Crosse
MQT Algorithm Summary
 SPT Wheal Size: > 9mm, No ID, Interpret as #6
EP
 SPT Wheal Size: 3-8 mm, Apply #5 ID
≤5mm, Interpret as #4 EP
 If 7-9mm, Interpret as #5 EP
 If ≥9mm, Interpret as #6 EP
 If
 SPT Wheal Size: <3mm, Apply #2 ID
≤6mm, Interpret as NEG
 If ≥ 7mm, Interpret as #3 EP
 If
Current in vivo and in vitro screens for inhalant allergy. KrouseJH, Stachler RJ,
Shah A. Otolaryngology Clinics of North America. 2003 Oct;36(5):855-68.
Copyright 2015 Allergy Associates of La Crosse
MQT Algorithm
Copyright 2015 Allergy Associates of La Crosse
Copyright 2015 Allergy Associates of La Crosse
Testing Technique Summary
Test
Efficiency &
Economy
Specificity
Sensitivity
SPT only
Yes
Yes
No
IDT
No
Yes
Yes
Optimized
IDT
MQT
(SPT+IDT)
Yes
Yes
Yes
Yes
Yes
Yes
Copyright 2015 Allergy Associates of La Crosse
Special considerations:
 Know your pollens
Copyright 2015 Allergy Associates of La Crosse
Special considerations
Know your regional pollens!
Copyright 2015 Allergy Associates of La Crosse
Special considerations:
 Know your pollens
 Use of Allergen Mixes in testing
Copyright 2015 Allergy Associates of La Crosse
Use of Allergen Mixes:
Testing & SLIT Considerations
 Testing with allergen mixes
 Reduces
the number of tests
 Takes advantage of cross-reactivity or coseasonality
 For SLIT
 Inducement
concern
Copyright 2015 Allergy Associates of La Crosse
of new sensitivities is not a
Use of Mixes: Testing and SLIT
Considerations
 Easy to describe “mixology”
 “Non
Cross-reacting Mix”-a combination of
non or slightly cross reacting allergens, i.e.,
ones that pollinate at the same time (Fall
Pollen) or are grouped by type (11-Tree Mix,
AA Mold Mix).
 “Cross-reacting Mix”-a combination of
highly cross-reactive major allergens, i.e.,
Mite Mix (equal parts Dp, Df) Ragweed Mix
(short, giant) or Standardized Grass (equal
parts antigen K grasses).
Copyright 2015 Allergy Associates of La Crosse
Use of Mixes:
Testing & SLIT Considerations
 Contrary to what is often recommended for


SCIT treatment, we liberally use mixes for
both testing and treatment
If your practice intends to provide both SCIT
and SLIT, then continue to test with single
allergens and treat the SLIT patients with
mixes, using the highest reacting constituent
allergen to determine the treatment level
Stay tuned, more to follow during later
presentations!
Copyright 2015 Allergy Associates of La Crosse
Special considerations:
 Know your pollens
 Use of Allergen Mixes in testing
 Recognizing atypical responses
Copyright 2015 Allergy Associates of La Crosse
IDT: Atypical Skin Test Responses
#6
#5
4
4
5
7
#4
#3
5
7
7
Endpoint
21
7
9
Endpoint
Copyright 2015 Allergy Associates of La Crosse
#2
#1
11
Special considerations:
 Know your pollens
 Use of Allergen Mixes in testing
 Recognizing atypical responses
 Recognizing & recording delayed
reactions
Copyright 2015 Allergy Associates of La Crosse
IDT: Atypical Skin Test
Responses (cont.): Late Phase
Reactions
Endpoint
5
7
Endpoint
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7
7
8
“Delayed”
IDT: Delayed Reactions
Day of Testing
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24 hrs later
48 hrs later
IDT: Delayed Reactions
Pt. J.S. 2 weeks
later
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Dr. Keith Eaton LRCP LRCS
1936-2002
Copyright 2015 Allergy Associates of La Crosse
Moulds, Yeasts, Ascospores,
Basidiospores, Algae and
Lichens: Toxic and Allergic
Reactions
 “…delayed reactions should be actively
sought in every patient. When this is
done it may be noted that moulds in
particular may be associated with
delayed skin responses, which take
various forms.”
Eaton, K . J Nutr Environ Med. 2002;12:321-335
Copyright 2015 Allergy Associates of La Crosse
IDT: Delayed Reactions
 Often occur in mold allergic patients
 Often occur in patients with chronic
sinus congestion, fatigue, aching,
headaches
 Can be effectively treated with
sublingual immunotherapy
 The safe treatment dose is the
strongest wheal dilution with no
significant delayed reactivity
Copyright 2015 Allergy Associates of La Crosse
IDT: Delayed Reaction Report
Card
Copyright 2015 Allergy Associates of La Crosse
Special considerations:
 Know your pollens
 Use of Allergen Mixes in testing
 Recognizing atypical responses
 Recognizing & recording delayed
reactions
 Special testing considerations
Copyright 2015 Allergy Associates of La Crosse
IDT: Special Testing Situations
 Young child: # tests=age +2
 Patient with history of systemic rxn from
prior allergy testing & patients on beta
blockers
 Do
std titration with few selected antigens
beginning at very weak dilutions (#’s 5,6,7)
 Patient recently on medications potentially
influencing skin test response
 Do
histamine control, consider: retesting off
meds, RAST/ELISA test
Copyright 2015 Allergy Associates of La Crosse
Skin Testing: Histamine Control
 Concentrate 6 mg/ml
 Dilution #1: .25 cc conc + 4.75 cc coca
 Will validate results by documenting skin
test reactivity, especially for
 Very
old or very young patients
 Patients with recent ingestion of medications
that may suppress skin test response
 Usually start with #3 dilution
Copyright 2015 Allergy Associates of La Crosse
IDT: Special Testing
Situations: Beta Blockers
 12 yr survey of fatal reactions to allergen injections


and skin testing: 1990-2001-- none receiving beta
blockers
 Bernstein DI, Wanner M et al JACI 113(6):112936, 2004.
AAOA sponsored study 2003-2008 : safety of
allergy IDT testing and treatment in patients taking
beta blocker medication
Dr. Veling, AAOA
 33 months, 21,000 tests IDT
 8 test reactions, incidence .04%, no deaths
Copyright 2015 Allergy Associates of La Crosse
IDT: Special Testing Situations;
Beta Blockers: AAAAI Position
Paper
“Systemic reactions to skin testing
are rare. Nevertheless, special
precautions, when appropriate,
should be taken when the patient
needs sensitivity testing and cannot
stop treatment with a beta-blocking
agent.”
Copyright 2015 Allergy Associates of La Crosse
Causes for INCREASED ID reactions
on FOLLOW-UP IDT/MQT testing
 Falsely suppressed tests on initial visit due to pre




medication
IAQ issues in home: Increased exposure from indoor
allergen contamination (animals, dust, mold) in interim
IAQ issues at worksite: “Sick Building” with increased
allergen exposures in interim since seen
High allergen load engendered by recent personal activity
immediately preceding f/u testing
Testing of seasonal allergen “in season” on f/u visit,
whereas it was tested pre-seasonally on first visit
Recent ingestion of a cross-reacting food allergen
Copyright 2015 Allergy Associates of La Crosse
False negative inhalant tests
 Localized IgE production can exist!
 Remember the skin test is a “surrogate
marker” for reaction in other parts of
the body
 Some patients (allergic conjunctivitis)
may have minimal skin test reactivity
but still react in the eyes
Copyright 2015 Allergy Associates of La Crosse
Skin test “memory”
 Remember skin test sites have a
“memory” (skin resident memory
t cells)
 An allergenic exposure may trigger a
reaction at prior skin test sites
 Most often caused by molds
 Example: A boy who mows the lawn
Copyright 2015 Allergy Associates of La Crosse
Tools of the Allergist
 Skin Tests
 Scratch
 Skin
Prick Test
 Intradermal (ID, IDT)
 In Vitro Tests
 Specific
IgE
RAST (radioallergosorbent test)
 ELISA (enzyme-linked immunosorbent assay)
 Phadia diagnostic component testing

 Total
IgE, other tests
Copyright 2015 Allergy Associates of La Crosse
In Vitro Tests
 Types of tests
 Principles & mechanisms
 Advantages/disadvantages
 Indications
 Scoring
 Sample panel & hints
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Discovery of IgE
Kimishige & Teruko Ishizaka,1967
Copyright 2015 Allergy Associates of La Crosse
Types of In Vitro Tests
Assays for total IgE or allergen-specific IgE
 RAST (radioimmunosorbent test)
 Introduced
in 1972
 With minor exceptions, now obsolete,

“RAST” acronym persists!
 ELISA (enzyme-linked
immunosorbent assay)
 Variety
of commercial systems in use
 Each use different technology to bind
IgE to a surface, tag & meas
Copyright 2015 Allergy Associates of La Crosse
ELISA test
 In 1980s, more than a dozen
commercial test systems existed
 Current main methods:
 TurboRAST
(Agilent Tech)
 Immulite (Siemens Medical)
 ImmunoCAP (Thermo Fisher)
 Hycor UltraSensitive EIA

Note: results from different systems are not always comparable
to each other, even if provided in the same units
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ELISA measures unbound IgE
in the allergic Cascade
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ELISA Testing: Summary
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ELISA Testing: Technique
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In Vitro Tests: Advantages
 No risk to patient
 Less time-consuming than skin tests
 No interference by drugs
 Quantifiable measure of IgE antibody
which can be followed with treatment
 Ideal for assessing systemic IgEmediated food allergy
Copyright 2015 Allergy Associates of La Crosse
In Vitro Tests: Disadvantages
 Reimbursement restrictions, such as




limitations on number of tests performed
Lab-to-lab variability
Results not immediately known
No information provided on “delayed
reactions”
Measures IgE in blood and not a specific
organ “surrogate marker”
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In Vitro Tests: Diseases with
high yield
 Atopic Dermatitis
 Chronic Respiratory/sinus congestion
 Asthma
 Recurrent infections
 Chronic gastrointestinal symptoms
 Chronic urticaria
 Anaphylaxis
Copyright 2015 Allergy Associates of La Crosse
In Vitro Tests: Indications
 Infants, uncooperative patients
 Patients on antihistamines and other
medications causing skin test
suppression
 Pts with severe risk of anaphylaxis
 Pts with extensive skin disease,
dermagraphism
Copyright 2015 Allergy Associates of La Crosse
Typical IgE Modified Class System
Specific IgE Class
Conc in IU/ml
Neg
1/0
1
2
<0.05
0.05-0.08
0.08-0.15
0.15-0.50
3
4
5
6
0.50-2.50
2.50-12.50
12.50-62.50
>62.60
Copyright 2015 Allergy Associates of La Crosse
Interpretation
Absent
Equivocal
Low
Increasing Levels
In Vitro Test Interpretation:
Clinical Considerations (Cont)
 “After additional analysis, if the ELISA test
results (or skin testing) remain inconsistent
with the patient’s clinical history, the
overriding criteria in making the final
diagnosis should be the clinical history and
physical examination…”
Pearls and pitfalls of allergy diagnostic testing: report from the
ACAAI/AAAAI Specific IgE Test Task Force. Annals of Allergy,
Asthama and Immunology. Dec 2008;101:580-592.
Copyright 2015 Allergy Associates of La Crosse
Thank you
Next:
Break followed by
La Crosse Method Practice Protocol
Dosing Guidelines for Inhalant
Allergies
Mary Morris MD
Copyright 2015 Allergy Associates of La Crosse
Thank You
Copyright 2015 Allergy Associates of La Crosse