Allergy testing is important for diagnosis of allergic conditions. Skin prick tests and blood tests like specific IgE tests can help identify triggers. Specific IgE tests like ImmunoCAP are more accurate than total IgE and are not affected by medications, skin conditions, or pregnancy. Phadiatop is a useful screening test to detect sensitization to common inhalants and foods. Positive results on screening tests should be followed up with customized allergen panels based on symptoms and environment. Reference lab data shows significant prevalence of sensitization to common allergens like dust mites, pollens, foods in the local population tested. Proper history and examination along with selection of right allergen panels is key to allergy diagnosis

1. ALLERGY TESTING –For Diagnosis
Dr Rajesh V Bendre
CHIEF PATHOLOGIST
MD(Path), DNB(Path), DPB

2. Allergy
 Von Pirquet define allergy as “the
ability to develop altered responses
to foreign substances after
repeated exposure” All of the risk
factors for allergy are not known,
but genetic and environmental
factors are of importance.
 Tendency to suffer from allergic
conditions is called Atopy.
 Gell and Coombs identified
allergic responses as Type I or
immediate hypersensitvity
reactions
 This allergic response occurs at
mucosal interface between
external environment and internal
milieu

3. Indian Data of Allergy Prevalence
 Statistics in India on the
prevalence of allergic diseases
shows10 to 15 percent suffer
from some form of allergic
disease.
 About 2 to 8 % of Indian
population suffers from asthma
with or without rhinitis
 Food allergies – 2 to 5%
(VP chest data;R kumar 2010)
 Drug allergies – not known
(Generally < 1%)
 Children allergies – About 30-
40%
INCREASED PREVALENCE
WHY?
• Hygiene hypothesis –
• Infection – burden reduced
due to use of vaccinations and
Antibiotics,
• Increasing Environmental
pollution
• Lifestyle- Urbanisation,
Eating habits
• Migration of people

4. Allergic Diagnosis- Symptoms
.
Food Allergy
Atopic dermatitis
(Eczema)
Allergic
rhinoconjunctivitis
(hay fever)
Asthma
(cough;
wheeze)
Gastrointestinal
symptoms
Nervous system:
Headaches
Irritability
Anaphylaxis
Muscle pain

5. Allergy Diagnosis- Concepts-
Allergy March
Allergy March - natural history of
sensitisation of allergens and symptoms
of eczema, asthma, and rhinitis which is
characterised by a typical sequence of
sensitisation and manifestations of
symptoms that appear during a certain
period.
Food allergy and Atopic eczema
during the first few years of life have
been considered risk factors for
subsequent asthma and rhinitis caused
by indoor and outdoor inhalant allergens,
Prevalence of Skin allergy deceases
with age. In contrast respiratory
allergy increases with age

6. Allergy Diagnosis-
Cross-Reactions - Between
Inhalant Allergens and Food Allergens
Inhalant Allergy Food Allergy
Birch pollen Nuts, apple, pear,
peach, plum,
cherry, carrot,
peanut, soy
Ragweed pollen Melon, banana
Grass pollen Tomato, peanut,
pea, wheat, rye
Latex Banana, chestnut,
kiwi, avocado
Chironomids Crustaceans
Van Ree R. Curr Opin Allergy Clin Immunol,
2004;4:235-40
• Many allergens are glycoproteins
containing oligosaccharide side
chains which are bound to the
protein framework of these
allergens. In some cases, patients
develop specific antibodies against
these carbohydrate structures.
• The abbreviation CCD stands for
“cross-reactive carbohydrate
determinant” can be found in a
large number of allergens of
vegetable or animal origin. Due to
their significant similarity in
structure, CCDs are known to
cause a strong crossreactivity.

7. Allergy Diagnosis –
Food Allergy versus Food Intolerance
 Food allergy is type 1 or immediate hypersensitive reaction
 It occurs immediately after food intake and GIT, rhinitis, asthma , skin
problems occurs which is IgE mediated
 Most common food allergens- Cows milk, Eggs, Soyabean, Wheat ,
shrimp, Fruits, peanuts, walnut
 Food intolerance is IgG mediated and has other mechanisms. It is slow
response and causes mainly GIT symptoms. E.g – Lactose intolerance,
Gluten intolerance

8. Allergy Diagnosis –
Drug Allergy versus Adverse Drug Reaction
• Type AADRs which are predictable and dose dependent, comprise up to
80% of all ADR.
• Type B ADRs are unpredictable, dose independent and comprise 20% of
all ADRs. These may include immunologically mediated drug
hypersensitivity (Drug allergy) or non-immune mediated/ idiosyncratic
reactions
• The World Allergy Organization (WAO) 2003 defined ‘drug allergy’ as
an immunologically mediated drug hypersensitivity reaction. The
mechanism may be either IgE or non-IgE mediated, with T-cell mediated
reactions largely represented in the latter.
• The true incidence of drug allergy is not known but often less than 1%.
• The most common DHR involve antibiotics like Penicillin,
Cephalosporins, Sulfonamides, Aspirin and NSAIDS.

9. Allergic Diagnosis

10. Skin prick test or blood test?
 Both SPT and in vitro tests vary in their ability to
detect sensitization depending on:
 the quality of the extracts used
 the stability of the extracts used
 the technical detection limit of the test
 Variable standardisation
 SPT is a tool mainly for experienced clinicians
 Limitations of Skin prick test: It Cannot be performed in acute
eczema cases. To Stop antihistamines 2-3 days before.
 Interpretation of results is crucial step for the tests.

11. Total IgE versus Specific IgE
 Total IgE is 50 %
Sensitive and specific
 Causes of increase Total
IgE is increased in
parasitic infection,
allergy, post surgery,
inflammation.
 Total IgE does not pick
up sensitisation
 Normal total IgE does
not rule out allergy
• Phadiatop (Adult & Child) is 90 %
sensitive and specific
• Specific IgE blood tests can be
performed irrespective of a patient’s
age, skin condition, and
antihistamine medication and even
during pregnancy.
• IgE antibodies appear in human
serum and plasma as a result of
sensitization to a specific allergen.
Measurement of specific IgE
provides an objective measurement
of the sensitization to the allergen.
Quantitative results (KUA /L)

12. ImmunoCAP® testing
 Can be performed irrespective of:
 Age
 Symptom
 Disease activity/or severity (e.g. active
eczema)
 Antihistamine/steroid medication
 Pregnancy (hormone influence)
 Is calibrated to WHO ref. preparation for
IgE
 Gives true quantitative levels (kUA/l)
 FDA approved
 High binding capacity of allergen proteins
including those in very low levels - 3-dimensional cellulose polymer.
- Covalent coupling through CNBr-
activation
- High binding capacity upto 150
allergens
ImmunoCAP is an FluoroenzymeImmunoassay

13. Immunocap- comparability- C. Vidal, et al.
J Invest Allergol Clin Immunol 2005;Vol.15(2):124-130

14. Phadiatop- Screen
 Phadiatop is a blood test designed to differentiate between atopic
and non-atopic patients.
 It is a multiallergen screening test utilizing patented sensitive
technology Immunocap and detects the presence of specific IgE
antibodies to common inhalant allergens and few food items.
 It has well balanced mixture of allergens specific to age and
region. It utilizes cross sensitisations and co- sensitisations
principle to cover most of allergens.
 As compared to skin prick allergy testing, it is non invasive
method of screening for allergy.
Phadiatop Adult ( > 5 years) – common inhalant allergens like grass,
weeds, trees, animal, mites and molds
Phadiatop infant < 5 years – Food allergens with inhalant allergens

15. Allergy testing- Approach
 Clinical history : symptom
wise, duration
 Clinical examination:
redness , rash, wheeze etc
 After screening with
phadiatop individual panels
can be selected –
 As per symptomology.
 Regional panels -
Preemployment, Travel,
migration patient has to
know what allergens are
there in that environment.

16. Individual Allergens
INTERPRETATION-
• A positive result confirms
presence of Atopy.
• Distinction must be made
between sensitisation and
allergy (clinical reaction).
“cut points” in specific
IgE results aid in
categorisation of patients
with severity of allergy
symptoms or sensitization
• For further workup of a
positive result customized
allergy panels based on
age, symptomatology,
environmental,
geographic factors are
recommended.
• A negative result means
symptoms are not due to
allergy.

17. Cut points that will predict with 95% accuracy those patients that will react, are
specific IgE results (Sampson HA, Ho DG, J Allergy Clin Immunol 1997, 100, 444-51).
Individual Allergens

18. REFERENCE LAB DATA
TEST Total 6 mths data negative Total 6 months data positive
Total test
received
Percentage
positive
Phadiatop Adult 1071 1053 2124 49.57 %
Phadiatop infant 50 55 105 53.38 %
Aspergillus fumigatus 318 169 487 34.7 %
Candida albicans 143 21 164 12.8 %
Cladosporium h. 222 16 238 6.72 %
Penicillium notatum 112 7 119 5.88 %
Alternaria alternata 111 8 119 6.72 %
D.farinae 259 261 520 50.19 %
D. pteronissinus 263 260 523 49.71 %
House dust ( Greer ) 312 138 450 30.67 %
Cockroach German 240 167 407 41.03 %
Shrimp 191 66 257 25.68 %
Tuna 207 9 216 4.16 %
Cod fish 251 6 257 2.33 %

19. TEST total 6 months negative total 6 months positive
total test
received percentage positive
Cow Milk 385 60 445 13.48 %
Wheat 326 54 380 14.21 %
Peanut 257 29 286 10.14 %
Soyabean 338 34 372 9.14 %
Potato 176 18 194 9.27 %
Rice 256 26 282 9.22 %
Lentil 217 27 244 11.07 %
Egg white 298 26 324 8.02 %
Egg Yolk 175 3 178 1.68 %
Banana 40 8 48 16.67 %
Pineapple 176 20 196 10.2 %
Lemon 221 30 251 11.95 %
Casein 41 8 49 16.33 %
Dog dander 424 57 481 11.85 %
Cat dander 454 33 77 6.91 %
Cow dander 115 16 131 12.21 %
REFERENCE LAB DATA

20. TEST total 6 months negative total 6 months positive
total test
received
percentage
positive
Cultivated Rye 157 22 179 12.29 %
Corn / maize 29 7 36 19.44 %
Cynodon grass (durva) 100 46 146 31.51 %
Mustard (Sarson) 177 11 188 5.85 %
Common ragweed (Close to
parthenium) 96 23 119 19.33 %
Sorghum grass (Jowar grass) 88 31 119 26.05 %
Prosposis juliflora (Mesquite) 87 10 97 10.31 %
Ampicillin 54 3 57 5.2 %
Penicilloyl G 57 0 57 0%
Penicilloyl V 57 1 58 1.7 %
Insulin 57 1 58 1. 7%
Total (10 months) 9043 2282 11325 20.15 %
REFERENCE LAB DATA

21. References-
1) Maria Bohme et al. Clinical features of atopic
dermatitis at 2 years of age : a prospective , population
based case control study. Acta Derm Venereol;81:193-197
2) Ballardini et al. Immunocap Phadiatop infant – a new
blood test for detecting sensitisation in children at 2 years
of age. Allergy 2006; 61: 337-343
3) WAO white book on allergy 2011-2012 : executive
summary
4) C. Vidal et al. Evaluation of Phadiatop test in diagnosis
of allergic sensitisation in general adult population. J
invest Allergol Clin Immunol 2005 15 (2) : 124-130

22. THANK YOU