1. Diagnosis of type 1 allergy.
Prof. Mohamed Osman Gad ElRab .
College of Medicine & KKUH .

2. Introduction :
Many patients with various مختلفه clinical problems are suspected to have an allergic disease , يعني اذا جاك مريض حط من اعتباراتك انه عنده حساسيه واغلب هذولا المرضى هم : e.g. . - itching skin rashes. - upper & lower respiratory symptoms . - adverse reactions to food . - adverse reactions to drugs,(antibiotics, local anesthetics, analgesics ).

3. Establishing a correct allergy diagnosis help to
select appropriate therapeutic interventions for
the patient such as :
اشهر انواع علاج الحساسيه :
- allergen avoidance تجنب مثيرات الحساسيه .
- medications .
- immunotherapy .

4. Major indications دواعي الاستخدام الاساسيه for allergy testing .

5. are not controlled by medications .
1. patients with rhinitis in whom symptoms
are not controlled by medications .
allergic rhinitis .( IgE- mediated ). ( هذا النوع هو اللي نبحث عنه بعمل الاختبار وهذا النوع هو اللي ما يستجيب للعلاجات العاديه )
non-allergic rhinitis .( non IgE- mediated ) .
infectious aspirin hypersensitivity. non-specific.

6. Prevalence معدل الانتشار :
60 – 70 % of rhinitis patients have
allergy ( IgE- mediated ).
25 – 34 % of patients with rhinitis develop
asthma within 10 years .

7. 2. patients with persistent دائم symptoms of asthma .
58-80% of asthma patients have immediate
skin test reactivity .
.(Kalliel etal. Chest 1989,96: ).
58% of adult asthmatic patients in Riyadh
have immediate skin test reactivity & specific
IgE to prevalent منتشرهallergens.
(Gad EL Rab M.O., Annals of Saudi Medicine.1999,19: ).

8. It is recommended that all asthma patients
,who require daily therapy ,be evaluated for
allergens as possible contributing مساهمه factors .
Guidelines for the diagnosis and management of asthma : expert
panel report NIH publication no ,Bethesda,Md.,1997: 43,45

9. 3. patients with suspected food allergy .
- adverse reactions to food proteins are divided
into :
IgE- mediated
non- IgE mediated .( food intolerance ). عدم تحمل الطعام مثل بعض الناس اللي يواجهون مشاكل مع حليب الجملات ( ياااي )
- approximately 5-6 % of children (younger than
3 years ) and 1.5 – 2 % of the general population
suffer from food allergic disease .

10. Diagnosis of food allergy is important because the mainstay الدعم الرئيسي of therapy remains :
1. avoidance of the incriminated المسبب للحساسيه ( بعض الناس حساسين من الفول ) foods. 2. education to deal with inadvertent exposure التعليم للتعامل مع الحالات المفاجئه ( واحد اكل اكل ما درى انه يسبب حساسيه ) .

11. 4. patients with suspected drug allergy .
- reliable فعال ودقيق allergy tests for drugs are available only for penicillin and local anesthetics التخدير الموضعي. مهمه جدا
- e.g. suspected reaction to penicillin .
prescribe يوصف له alternative antibiotic مضاد حيوي آخر .

12. 5. suspected insect sting reactions :
previous suspected systemic reaction to insect
stings .
- identify insect .
- advice immunotherapy. لان الحشرات من
مثيرات الحساسيه التي لا يمكن التحكم بها ( يعني مب على
كيفك ما تاكل حشرات )
- e.g. the honey bee & black fire ant
are common causes of anaphylaxis.
الحساسيه المفرطه والتي من الممكن ان تؤدي للوفاه وتعالج بـ
Epinephrine ( adrenalin )

13. Types of allergy tests :
1. Immediate- type hypersensitivity skin testing . a. percutaneous route .( skin prick test ). b. intradermal route .( injection of allergen within the dermal layer ). 2. assay قياس for allergen specific IgE antibodies .

14. 3. Bronchial challenge test . ( occupational asthma الربو المفتعل )
- expose patient to allergen and record symptoms.
4. Double- blind food challenge test .
provide definitive النهائي diagnosis of food allergy
when clinical certainty الاعتماد والتاكيد is needed .
( because of the low specificity of the skin test
with food allergens ).مهمه

15. 1. the skin prick test ( SPT ) (the most commonly used method ) .
1. rapid. 2. accurate دقيقه . 3. cheap. 4. safe procedure. اجراءات 5. highly reproducible . تعطي نتائج

16. Principle المبادئ of the skin test :
when allergen extracts are introduced into the skin ,of a
previously sensitized individual , they
cross- link IgE molecules on mast cells which :
release mediators and produce :
- a local wheal and flare reaction .

17. Site for prick test اماكن الوخز :
The inner (volar الراحه ( الباطن )) aspect of the forearm.
Or :
The skin of the upper back.
يستخدم هذا المكان فقط عند:
- in dermatitis of forearm .
- children with small forearms.

18. Contraindications موانع استخدامه to skin prick testing:
Do not apply skin prick tests to patients when there is convincing history of anaphylaxis to the test allergens.
this is particularly important in :
Nut جوز ( مكسرات ) allergy.
latex افرازات بعض النباتات allergy .
horse allergy.
drug allergy .
severe food allergy.

19. Other contraindications:
1.Diffuse dermatological condition. عرض او مشكله جلديه منتشره
2. Patient unable to stop medications .
( anti-histamines inhibit the wheal& flare reaction
patients advised to stop the drug 3-10 days before
skin testing ) عشان ما يمنع هذا الدواء ظهور نتائج الاختبار

20. 3. during pregnancy.
3. poor patient cooperation .
4 .Severe dermatographism
ارتيكيريا ناتجه عن مؤثر فيزيائي
مثل كثره الحك و الدخان ( مثل اللي يطلع
اذا لبست حرام ) .

21. Interpretation تفسير ميكانيكيه of the skin test .
Positive control skin test ( histamine )
Negative control skin test (diluent )
( essential for correct interpretation) .
-15 minutes after application of allergen,
examine test site for a wheal and flare .
- a positive reaction = a wheal 3 mm or greater
in diameter + erythema .

22. Selection of allergens for testing
Selection of allergens for testing There are over 400 allergens known to cause allergic disease Selection is based on : medical history prevalent المنتشره allergens in the area .

23. SPT is safe ,but the following emergency resuscitative equipment must be available :
* Injectable Adrenaline 1:1000. الاهم * Oxygen . * Oral Phenergan دواء مضاد للهستامين & injectable. * Hydrocortisone . * Inhaled bronchodilator.

24. Number of allergens and age:
* عدد المثيرات : Any number from 1-40 allergens may be tested in a single session . *عمر الاشخاص : Consensus الاجماع ينص على أنه indicates that the tests are of value from 4 months of age onwards . However, Infants & the elderly tend to have a less reactive skin.

25. الاختبار الثاني Multi – test device:
: أولاDip غمس applicator in allergen tray صينيه. : ثم ثانيا Apply with pressure on the arm. a positive test: = 4.5 mm. wheal diameter. ( preferred by patients.) لاحظ انه لا ينتج حمره ( احمرار ) وان القطر اكبر من الاختبار السابق

26. Correlation العلاقه بين between :. size of skin test
Correlation العلاقه بين between : * size of skin test * degree of IgE sensitization * clinical symptoms.
90 % of patients with a wheal = 5mm. react positive on provocation اثاره tests & the allergen tested is involved in clinical disease .

27. *High non-specific reaction rate.
: الاختبار الثالث Intradermal test : used for investigating : يستخدم للكشف عن : insect sting allergy drug allergy hg
*High non-specific reaction rate.

29. 2. Not affected by medications. 3.Preferred in patients with high risk
الاختبار الرابع : allergen - specific serum IgE test . ( also called RAST test – radioallergo-sorbent test )_
Advantages:
1. No risk of reactions.
2. Not affected by medications.
3.Preferred in patients with high risk
of reactions:
-unstable asthma.
-anaphylaxis.
-sting insect allergy.

30. 1. Expensive. Disadvantages : 2. Less sensitive than SPT.
3. Difficult to interpret الكشف in patients with high level of total IgE (1000 KU/ml )

32. Specific IgE (RAST) results are reported in classes :
class o : no specific IgE detected. class 1 : low level . class 2-4 : moderate level . class 5-6 : high level .

33. The spread of total IgE values is very wide
Total serum IgE.
The spread of total IgE values is very wide
and reliable upper limits distinguishing
non-atopic and atopic could not be
established .
* Useful in large epidemiologic studies.
* Not applicable in the clinical evaluation
of individual patients.

34. Conditions with elevated total IgE :
These may include : 1. certain immunodeficiency disorders . 2. parasitic infections . 3. certain types of T-cell lymphomas . 4. atopic dermatitis . 5. eosinophilic lung disease .

35. Positive skin test reactions with no symptoms affect 8-30 %
These reactions may indicate :
1. past sensitization .
2. latent الكامنه allergy . .

36. Prospective سابقه studies in Denmark showed that
30 to 80 % ( of asymptomatic patients with positive skin test become allergic depending on :
allergen exposure.
*have prognostic ( preventive) value.
Bodtger U; Current Opin Allergy Clin Immunl,2004;4(1):5-10.

37. Summary :
1. diagnosis of allergy determine line of treatment e.g. avoidance of allergen, immunotherapy . 2. skin test reactivity should be correlated مربوط مع with clinical sensitivity .

38. 3. definitive diagnosis of food allergy is by
double-blind challenge tests . مهمه
4. administration of allergy vaccines require
accurate identification of causative
allergens .(immunotherapy ).