Skin prickly test is the most useful, easiest and affordable investigation to identify the suspected allergen as to the cause of sensitisation … it will detect bound IgE … it is preferred to immunocap assay test…

1. Allergy testing of
pediatric airway allergies
in Children
Dr.G.Sudhakar
Professor of Pediatrics (Rtrd)
Consultant pediatrician
KIMS Hospitals
Kurnool
Part of information is from Lectures of Dr.P.K.Vedanthan and Dr.Balachandra

2. The learning objectives of todays interaction…
• What is atopy, sensitization and allergy?
• What is allergy skin testing?
• How do we identify the suspected allergens as the cause of illness?
• Various modalities of allergy testing?
• What is the basis of skin prick testing?
• How do we do SPT?
• How to interpret SPT results
• Scope of SPT in Pediatric practice?

3. Who is the legend first performed this skin
prick test for diagnosing allergies?
•Charles Harrison Blackley
•1860s in his research studies on “Hay fever”

4. Allergy definition…
• Altered or exaggerated reaction (Body response)
• Against harmless substances (antigens)
• With production of IgE antibody ( Immunological response )
• Which can be protective or harmful (allergic inflammation)

5. Certain terms need clarification…
• Atopy is a genetic term. Reflects genetic endowment of a child by
virtue of parents or grand parents having allergic illness
• Sensitization is an immunological term. A child may be sensitized to a
particular allergen after an exposure. It means that an IgE specific to
that particular allergen is present on the surface of mast cells in the
tissues.
• Allergy is a clinical term, meaning that child manifests features of
allergy after re-exposure to an allergen to which child is already
sensitized.

7. Some facts but confusing…
• A child can be atopic but not allergic
• A child can be sensitized but not allergic
• A child can be allergic but not atopic
• A child if allergic is always sensitized

8. Which Patient should under go Allergy Test
• Children With Allergic Rhinitis
• Children With Atopic Asthma
• Children With Allergic Conjunctivitis
• Children With Moderate to Severe Atopic Dermatitis
• Children With Food, Insect, Drug Allergies
• Children with h/o of Anaphylaxis
( indicated in all with IgE mediated allergic clinical
conditions )

9. Which test to do? The diagnostic pyramid
History and physical examination
Allergy Skin prick tests
Allergen specific serum IgE
Basophil activation test
Organ challenge
Provocation
test
Serum Total IgE not Very
Useful
Sohrab S, et al. Allergo J 2013;22(2):128-34.
Bernstein IL, et al. Ann Allergy Asthma
Immunol. 2008 Mar;100(3 Suppl 3):S1-148.
suitable for clinic setting
suitable for clinic setting

12. Skin Prick
Test
Serum specific
IgE test
Quick results
 
Clear demonstration to patients of their
allergies
 
Better sensitivity and specificity
 
No interference from high total IgE*
 
Recommended as diagnostic test of
first choice by various authorities
 
*False positives possible with high total IgE levels in serum specific
IgE tests
Bousquet J, et al. Allergy 2012; 67: 18–24; Bernstein IL, et al. Ann Allergy Asthma Immunol. 2008
Mar;100(3 Suppl 3):S1-148.
ASCIA Skin Prick Test Manual. 2013. Heinzerling et al. Clinical and Translational Allergy 2013, 3:3
Skin Prick Test vs Serum Specific IgE Testing:
Favoring Skin Prick Test

13. Diagnostic Tests – Skin Prick Test (SPT) as the First Choice
Bousquet J, et al. Allergy 2012; 67: 18–24. Bernstein IL, et al. Ann Allergy Asthma Immunol. 2008 Mar;100(3 Suppl 3):S1-148. ASCIA Skin Prick Test
Manual. 2013.
Global Allergy and Asthma European Network (GA2LEN); Allergic Rhinitis and its Impact on Asthma
(ARIA)
EAACI Position Paper 2012
Skin tests represent the first diagnostic method in patients with a
suggestive clinical history of allergic rhinitis (conjunctivitis) and/or asthma
American Academy of Allergy, Asthma and Immunology (AAAAI) &
American College of Allergy, Asthma and Immunology (ACAAI) - 2008
Prick/puncture tests are the preferred techniques for IgE-mediated
hypersensitivity
Australasian Society of Clinical Immunology (ASCIA) 2013
Skin prick testing (SPT) is recommended as the primary method for the
diagnosis of IgE mediated allergies in most allergic diseases

14. IMMUNOCAP ASSAY TEST

15. What is allergy skin testing?
• It is real time bioassay of bound IgE over the mast cells at entry point
of allergen into the skin
• We deliberately introduce suspected allergen into the superficial
epidermal layers of the skin
• If the child is already sensitized to that allergen there must be mast
cells, with surface IgE antibodies specific to that allergen, located at
all allergen entry points including the superficial layers of the skin.
• Soon after the allergen is introduced, the allergen is picked-up by IgE
molecules on surface of sensitized mast cells, degranulation of mast
cells and histamine release occur at allergen entry point itself
producing an induration of wheal.
• This occurs usually with in 15min of entry of allergen. This induration
is measured and compared to positive and negative controls
• If induration is significant, we mean child is sensitized to that allergen

16. The IgE antibodies station
themselves over the surface of
mast cells which are present
only in tissues not in blood
Initial Exposure sequence

17. Re-Exposure sequence

18. AST detects only sensitization to a tested
allergen...

19. • Case A - 6 year old child came to
Office with h/o of recurrent Cold and
cough and fever, child gets an Episode
once in 20 days recovers after 1 wk and
later gets an Episode within a months
time while going to School,
• Child is normal in the interval period,
No Family History of Atopy
• Case B - A 6 year old Child come with
History of Recurrent cold, cough and
fever at an Interval of 15 to 30 days,
Child Sneezes every day in the morning
hours since 1 year and gets wheezing
during his Fever Episode, and during
activity.
• Child also has Eczema and Father is a
Known Asthmatic
Parents brought their children for Allergy Test as referred
by a paediatrician Which patients should undergo Allergic
Test ? Patient A or B or Both
Allergy Test – How to Select A patient

20. What are the techniques?

24. Skin Prick Tests:
Method
T
O

27. How to Select a Short Relevant Aeroallergen Panel:
Know the % Burden & Indian Prevalence of Allergens
~50%
House dust mite
~20-25%
Pollen
~7-10%
Mould
~10-20%
Insects
<5%
Animal Dander
Cumulative references from Indian literature and personal communication with clinicians
HDM contribute to sensitizations and allergies in 50-70% of the allergic Indian patients.
Pollen 20-30%

28. House Dust Mites
~50%
Mite
D. pteronyssinus
D. farinae
Blomia tropicalis (nonstandardised)
Acarus siro
Tyrophagus putrescentiae
Lepidoglyphus destructor
(Standardized allergens are available except for Blomia tropicalis)
Dermatophagoides Acarus siro Blomia tropicalis

29. How to Select a Short Relevant Aeroallergen Panel
~20-25%
Pollen Grass Pollen
Weed Pollen
Tree Pollen
Points to remember:
• Cross-reactivity
• Local prevalence (eg. Himalayan Pollen)
Singh AB. Global Journal of Immunology and Allergic Diseases, 2014;2:19-28.

30. Important Allergenic Grasses
Phleum pratense Poa pratensis Lolium perenne
Imperata cylindrica
Cenchrus cilaris
Cynodon dactylon Zea mays

31. Important Allergenic Weeds
Parthenium hysterophorus
Artemisia vulgaris
Amaranthus spinosus
Chenopodium album
Plantago
Urtica dioca

32. Important Allergenic Trees
Prosopis juliflora Holoptelea integrifolia

33. How to Select a Short Relevant Aeroallergen Panel
~7-10%
Mould
Alternaria alternata
A. fumigatus
Penicillium
Cladosporium
Rhizopus nigricans
Helminthosporium
Fusarium
Mucor mucedo
Botyritis cenerea
Pullularia
Ansari MSS, et al. Biology and Medicine 2012;4(4):167–177.
Goyal M, et al. Indian J Allergy Asthma Immunol2010;24:1-6.
(Standardized allergens are available)

34. How to Select a Short Relevant Aeroallergen Panel:
Know the % Burden & Indian Prevalence
~10-20%
Insects
Periplanetta americana (American cockroach)
Blatella germanica (German cockroach)
Aedes (Mosquito)
Moth
nonstandardized allergens are available

35. How to Select a Short Relevant Aeroallergen Panel:
Know the % Burden & Indian Prevalence
~5%
Animal epithelia
Cat
Dog
Cow
Horse
Agarwal RL, et al. Indian J Allergy Asthma Immunol2008;22(1):7-13.
Goyal M, et al. Indian J Allergy Asthma Immunol2010;24:1-6.
(Standardized allergens are available)

36. Non-relevant Allergens: Guidance from the US FDA
 The Allergenic Products Advisory
Committee (APAC) in 1986
unanimously concluded that
“house dust extracts be
considered ineffective, unsafe
or misbranded”
 Byssinosis, a chronic narrowing of
the airways from exposure to cotton
dust is described in the literature
 It is not an IgE mediated illness
 No references to cotton gin dust
extracts for diagnosis or
immunotherapy were identified
House Dust Cotton Dust
http://www.fda.gov/downloads/BiologicsBloodVaccines/Allergenics/UCM272368.pdf
Such non-relevant allergen extracts should not be utilized

37. Why are standardized allergen extracts
required?
Cox et al. J Allergy Clin Immunol 2011;127:S1-55.
Non-standardized extracts can vary widely in biologic activity and composition, regardless
of a particular weight/volume or PNU potency, and should not be considered equipotent
1
The strength of a given concentration of non-standardized extracts might vary
significantly from lot to lot
2
The risk of systemic reactions might be greater with non-standardized extracts because
of this potential variability in the composition and/or potency
3
Non-standardized
extract units
PNU: protein nitrogen unit

45. Does positive ST mean allergy?

48. Influence of Anti-Allergic Drugs:
We need appropriate allergy diagnosis for initiating appropriate
management
Allergen contact
Effector cells of
allergic responses
Mediators of
allergic responses
Allergic symptoms
Corticosteroids
Antihistamines β2-agonist
Anti-IgE-Abs
Mast-cell stabilizers
Leukotriene receptor
antagonists Decongestive
Immunotherapy
These options only provide symptomatic treatment
Allergen avoidance and immunotherapy are the only treatments that modify the course
of an allergic disease either by preventing the development of new sensitivities or by
altering the natural history of disease or disease progression.
WHO Position Paper:

49. Allergen Immunotherapy Compared with Symptomatic Drug Treatment in Patients with
Allergic Rhinitis and Asthma
0
2
4
6
8
10
12
14
16
0 1 2 3 4 5 6
Symptom Score
Allergy Asthma Proc 27:159 –163, 2006
0
1
2
3
4
5
6
7
8
9
0 1 2 3 4 5 6
Medication Score
Years Years
*
**
** ** **
**
**
**
** ** **
* P=0.04; ** P<0.001
**
Only Drug Therapy Only Drug Therapy
Immunotherapy +
Drug Therapy
Immunotherapy +
Drug Therapy

50. Allergen Immunotherapy Compared with Symptomatic Drug Treatment in Patients with
Allergic Rhinitis and Asthma
0
200
400
600
800
1000
1200
1400
1 2 3 4 5 6
Differences in Overall Annual Cost
Allergy Asthma Proc 27:159 –163, 2006
Years
**
** **
** P<0.001
**
$
Only Drug Therapy
Immunotherapy + Drug Therapy

51. Summary…
• Allergic disorders are very common and constitute bulk of pediatric practice
• Allergic disorders manifest in children as atopic dermatitis, allergic rhinitis,
childhood asthma and food allergy
• Allergens can be of indoor or outdoor
• HDM (indoor with early morning symptoms) is the most common followed
by pollen (outdoor with evening symptoms)
• Skin prick test is cheap, quick, biological, preferred, and detects allergen
specific mast cell-bound IgE antibodies. Serum allergen specific IgE assays
detect free serum IgE.
• SPT positivity correlation with history is crucial
• SPT positivity denotes only sensitization but does not mean allergy
• When once allergen is identified, allergen avoidance measures and allergen
immunotherapy can be planned which can halt and may offer cure to allergy.

52. THANK YOU ALL
Yours
drgsudhakar@hotmail.com