Differnt lab investigations for allergy

1. Allergy tests

2. Raccoon
Eyes
Fatigue Depression
The Allergic Salute Trouble Concentrating
Chronic Congestion Wheezing
Hives
Itchy Skin Insomnia

3. Common symptoms of allergy
•Nose: swelling of the nasal mucosa
•Sinuses: allergic sinusitis
•Eyes: redness and itching of the
conjunctiva
•Airways: sneezing, coughing, Wheezing,
asthma, laryngeal edema
•Ears: feeling of fullness
•Skin: rashes
•Gastrointestinal tract: abdominal pain,
bloating, vomiting, diarrhea

4. cause
• Ingested allergens: Foods (peanut,
milk, soy, wheat, chicken ,egg , beef,
seafood, chesses , vegetables, fruits, …)
• Inhalant allergens: Pet danders, dust
mites, mold spores, pollen,cockroaches
• Other allergens: latex, drugs, insect
stings

5. Dust Mites
Animal Dander
Pollen
Molds Insect Stings
Foods Latex
Medication
Fragrance
Cockroaches

6. • Immediate hypersensitivities
• Antibody- mediated cytotoxicity
• Immune complex disorders
• Cell-Mediated hypersensitivities

7. ALLERGY TEST
• Skin test:
– skin prick test.
– Intradermal test.
– Patch test
• Blood tests: RAST, specific IgE antibodies level, elisa…
• Other tests:
Elimination type tests
Unproven allergy tests :
– Cytotoxic testing
– Provocation- neutralization
– Electrodermal diagnosis
– Kinesiology
– Reaginic pulse
– Body chemical analysis
– Measurement of IgG antibodies
– Histamine release assays

8. Contraindications for skin test
• History of anaphylaxis
• High risk of anaphylactic reaction to testing(
poor controlled asthma, reduced lung function,
history of severe reaction to minute amounts of
allergens)
• Rashes, acute skin injection
• Can not stop medication
• Cardiovascular disease( coronary artery, cardiac
arrhythmias)

9. Skin prick test
• The first choice
• Simple, quick, safe, sensitive, inexpensive
• Indentify inhaled allergens, ingested allergens, determine whether a person may be
allergic to a medicine or insect venom
• Place drops of the possible allergen on the skin
• Prick the skin under each drop with a needle
• Check the skin after 12 to 15 minutes for red, raised itchy areas called wheals
• The rate of systemic reactions to skin prick testing was 0,001%
• If skin prick test negative: choose intradermal test at a later visit

10. Intradermal test
• The intradermal test is sensitive more than the skin prick
test
• A small amount of the allergen solutions is injected into
the skin

11. Patch test
• Doses of the allergens are placed on the
patches that look like adhesive bandages
• Wear the patches for 24 to 72 hours, no bath, no
exercise
• Contact dermatitis

12. Blood test( immunoassay)
• Measure the mount of specific IgE, RAST, elisa
• When?
-Rick of an anaphylaxis.
-Rash(hives, eczema).
-Can not stop taking a medicine( antihistamine, tricycle
antidepressant, beta blocker, ACE inhibitor,
immunomodulatory creams, topical steroids)
-unusual and rare allergens are suspected
• Less sensitive than skin test
• Cost more than skin test

13. IDENTIFY POSITIVE TEST
• Positive skin test: a wheal created by the allergen
is at least 3mm larger than the reaction to the negative
control
• Positive blood test: the levels of immunoglobulin
IgE antibodies for a particular allergen or group of
allergens are four times the normal level

14. 50% and 95% Predictive Value have been
Established for Food Specific-IgE and SPT
Nowak-WÄ et al, Work Group report: Oral food challenge testing. J Allergy Clin Immunol 2009;
123:S365-S83.
Food specific-IgE measured with ImmunoCap™ and SPT with lancet (ref 17 & 21,) and
bifurcated needle (ref 22)

15. Specificity of SPT in predicting positive open food
challenges to milk, egg and peanut in children
Study: 555 challenges were undertaken in 467 children with
suspected food allergy. Positive challenge if objective signs seen;
negative, if the child could tolerate normal food daily, for 1 week.
Results: 55% were positive, 37% negative, and 8% inconclusive.
Possible to identify a SPT wheal at, and above, which negative
reactions did not occur (100% specificity ):
cow milk, 8mm
egg, 7mm
peanut, 8mm
However positive reactions could occur with a SPT of 0 mm.
Sporik et al, Clin Exp Allergy. 2000;30(11):1540-6.

16. Positive open food challenges to milk, egg and
peanut in children could occur with 0 mm SPT
Sporik et al, Clin Exp Allergy. 2000;30(11):1540-6.
MILK PEANUT

17. Diagnostic accuracy of skin prick
testing in children with tree nut
allergy
Study: 906 tree nut and peanut challenges in 680 child aged 4
month to 19 years
Results :
8 mm SPT weal diameters >95% accuracy in predicting a
positive OFC for cashew, hazel nut, walnut, and sesame.
Using the predictive SPT decision points, the need for OFC
was reduced by 33% (peanut), 56% (tree nuts), and 53%
(sesame),
Not able to determine the 95% PPV for almond, pistachio,
pecan, and brazilnut
Ho et al J Allergy Clin Immunol 2006;117:1506-8

18. The predictive value of the skin prick test
wheal size for the outcome of oral food
challenges.
Study: 735 OFC in 385 children (median age
22 months), with cow's milk, hen's egg,
wheat and soy.
Results: 312 (43%) OFC were assessed to be
positive.
95% and 99% predicted probabilities
using logistic regression revealed
predictive decision points of:
13.0 and 17.8 mm for HE
12.5 and 17.3 mm for CM
Verstege et al. Clin Exp Allergy. 2005;35(9):1220-6.

19. SPT Wheal Size May Useful in Predicting
Presence of Absence of Clinical Allergy
Study : Challenged 47 peanut-naïve children who had a positive SPT
to peanut (smallpox needle)
Results: 49% of challenges were positive
Mean wheal: negative group 6.3 mm vs. positive group 10.3 mm
Using the cutoff of a > 5 mm wheal on PST, peanut challenge yielded
Sensitivity was 100% (no false -)
Specificity was 12.5% (high false+)
Negative predictive value was 100%
Positive predictive value was 52%.
Conclusion: These findings suggest peanut PST of 3 or 4 mm could
undergo less resource-intensive, accelerated challenges.
19
Kagan R et al., Ann Allergy Asthma Immunol 2003 Jun;90(6):640-5:

20. Prediction of anaphylaxis during peanut food
challenge: usefulness of peanut SPT & specific
IgE
Study: 89 in-hospital challenges: positive in 56/89 (62.9%) patients:
In the 55 completed challenges: 28 no rx, 6 reaction without anaphylaxis, 21 had
anaphylaxis
Mean peanut SPT wheal size and specific IgE level were associated with the
severity of reactions on challenge
Wainstein et al . 2010;21(4 Pt 1):603-11

21. Allergy Skin Testing Advantages
• In the allergist office, skin testing remains the
central test to confirm allergic sensitivity.1
• Advantages:
• Skin testing is fast (15-30 minutes), safe, sensitive and
involves minimally invasive procedures
• Can provide information on allergen sensitivity on initial
clinic visit.
• i.e., no trip to a busy lab for venipuncture
• Cost-effective in terms of patient time & money
• When performed correctly, skin testing is reproducible
1. Oppenheimer et al, Ann Allergy 2006;S1:6-122.

22. Allergy Skin Testing Advantages &
Diagnostic Utility in Comparison to
Specific- IgE Antibody
• SPT may be more sensitive in predicting who will react
on challenge In pts with low food sIgE,
• SPT may have diagnostic utility
• SPT can identify sensitivity to labile food proteins

23. SPT Is Superior To IgE CAPRAST For The
Diagnosis Of Infantile Food Allergy
Study: Infants with suspected egg and milk allergy with negative
specific-IgE at the time of first visit
Results:
Egg: 72/89 (80%) suspected-HE allergies with negative IgE
CAPRAST, were diagnosed as HE allergy by the elimination and
provocation tests . 39 had positive egg SPT
Milk: 42/125 (33%) suspected-CM allergy infants with negative IgE
were diagnosed as CM allergy, and 21 (50%) had positive milk SPT
Authors’ Conclusions: “SPT seemed to be more useful than EW- or CM-
IgE CAPRAST for the diagnosis of HE or CM allergies in early infantile
period.”
Ebisawa M et al, J Allergy Clin Immunol 2009;123(2):S23.

24. Allergy Skin Test vs. In Vitro Tests
What about the side effects, risks and dangers?
24

25. Reactions to prick and intradermal
skin tests
Methods: 12-month prospective study was conducted to evaluate SRs from ST in 1,456 patients
Results:
Six patients (0.4%) had SRs during SPT. 1 reacted to aeroallergens alone, whereas the other 5
reacted to aeroallergens and food
No severe asthma, shock, hypotension, unconsciousness, or biphasic reactions occurred.
All 52 patients received epinephrine intramuscularly
Bagg A, Chacko T, Lockey R. Ann Allergy Asthma Immunol. 2009;102(5):400-2.

26. 26
Method: Retrospective study at the Mayo Clinic to identify patients
who developed systemic reactions to skin tests
Results:. 497,656 skin tests were performed : SPT 16,505 patients
6 patients experienced SRs. All had asthma.
SPT SR rate was 15 or 23 reactions per 100,000 aeroallergen tests
“It is noteworthy that there were no systemic reactions to skin tests for
foods or venoms”
Conclusion: SR to skin tests was very low. SRs were mild and all patients
recovered fully within 1 hour.
Systemic reactions to allergy skin tests
Valyasevi et al, Ann Allergy Asthma Immunol 1999;83:132–136.

27. Risk of adverse reactions from SPT, venipuncture,
and body measurements: NHANES II 1976-80
Study: 16,204 of the U.S. population , 6 to 74 yrs, examined with routine
medical procedures, including SPT & venipuncture.
SPT to 8 FDA licensed unstandardized extracts
Results:
SPT: No anaphylactic reactions after SPT were observed.
Venipuncture: One asthmatic reaction. Other AR limited to syncope,
near syncope, and malaise.
Adverse reaction rates:
Venipuncture: 0.49% (95% CI, 0.38% to 0.60%);
SPT: 0.04% (95% CI, 0.01%-0.08%);
Age group 20 to 49 years had the highest occurrence of any AR to
venipuncture (0.87%; 95% CI, 0.633% to 1.107%).
Turkeltaub J Allergy Clin Immunol. 1989;84(6 Pt 1):886-90

28. Allergy Skin Testing…moving into the future
Molecular Allergy: Can allergy skin tests meet the challenge?
• In 1930s, scarification - problem was a lack of uniformity in the abrasion AND
there was the potential side effect of scarring.
• Mueller device made six uniform abrasions 1-½ mm long and 15 mm apart
• Pepys modified prick skin test method in 1968.
• Studies comparing scarification to SPT showed increased false – and +
• As a result, use of the scarification technique diminished in 1970’s
Modified-Prick Puncture
Scarification Device
Multiplex Array

29. Component-resolved diagnosis of pollen allergy based
on SPT with profilin, polcalcin and LTP pan-allergens
Principle objective: evaluate a new diagnostic strategy - SPTs specific
for 3 pan-allergens, together with an appropriate and complete panel
of allergenic molecules.
Study :1329 pts with previous 2-year history of pollinosis, tested by
vitro method to 13 purified allergen including pan-allergens & SPT to
major allergens and pan-allergens
For SPT:
peach commercial extract adjusted to 30 mg/mL of Pru p 3, which is
a LTP
date palm extract: natural profilin, Pho d 2 adjusted to 50 mg/mL &
procalin

30. Component-resolved diagnosis of pollen allergy based
on SPT with profilin, polcalcin and LTP pan-allergens

31. Concordance of SPT extracts and sIgE to the
corresponding pan-allergens
Results:
Concordance of SPT extracts and sIgE evaluated: high diagnostic value is
observed for
Profilin SPT (positive and negative concordance 82.3% and 90.8%, respectively)
LTP-enriched SPT (positive and negative concordance 65% and 94.3% respectively ),
Polcalcin SPT performance lower (positive and negative concordance
50% and 90.4% respectively).
Authors’ conclusion: “ Novel diagnostic strategy has proven to be a
valuable tool in daily clinical practice. Introduction of routine SPT to pan-
allergens is a simple and feasible way of improving diagnostic efficacy.”
Barber et al,Clin Exp Allergy 2009;39:1764-73

32. Why Skin Testing is Superior to In
Vivo Testing Because:
More cost and time efficient for patient
Results available on initial consultation allowed for development of specific
treatment plan
Predictive value in terms of presence of clinical allergy and possible severity
In some cases greater predictive value than in vivo test
Ability to test to allergens that may be altered in extract preparation process e.g.,
natural foods
Can also be used in component-resolved diagnosis

33. Thank you