This document discusses the diagnosis of allergies in children. It covers the significance of allergy tests, various in vivo and in vitro diagnostic tests including skin prick tests, RAST tests, and patch tests. It also discusses the development of allergic diseases and different types of allergic conditions such as allergic rhinitis, asthma, eczema, and food allergies.

5. Normal and Atopic Normal Atopic Foreign Antigen Antigen Presenting Cell B & T lymphocytes Immunoglobulin Mast Cell Mediators TH1 TH2 IgE IgG, IgM eosinophil Mast Cell Histamine Leukotrine Cytokines eosinophil No change 2 nd difference 1 st difference

6. Development of Allergic diseases Environmental factors Atopic Immune Response In Utero Genetic Predispostion IgE Production Senstized Person Atopic Disease -Atopic dermatitis -Allergic Rhinitis -Asthma Environmental Allergen After Delivery

7. Mediators of Immediate Hypersensitivity attract eosinophil and neutrophils ECF-A kinins and vasodilatation, vascular permeability, edema kininogenase proteolysis tryptase bronchoconstriction, mucus secretion, vasodilatation, vascular permeability histamine Preformed mediators in mast cell granules: platelet aggregation and heparin release: microthrombi PAF edema and pain prostaglandins D 2 same as histamine but 1000x more potent leukotriene C 4 , D 4 basophil attractant leukotriene B 4 Newly formed mediators:

9. Allergic Rhinitis If the allergic reaction occurs at the nose, it results in congestion , nasal itching, sneezing & running nose.

10. URTICARIA / Skin If the allergic reaction occurs at the skin, it results in vasodilatation leading to Erythema , swelling & itching

11. Allergic Asthma If the allergic reaction occurs at the lung, it results in bronchial muscle constriction, increased mucous secretion leading to coughing, wheezing & difficulty in breathing

13. Atopic and Contact Eczema Atopic Eczema : Type I & Type 4 hypersensitivity reactions

14. Anphylaxis

16. Incidence of Allergic Disorders in UAE 1994 28% 14% % % %

17. Prevalence Of Allergic Diseases In Children (Europe)

18. Incidence Of Allergic Diseases in Children 2001 (Europe) 19% total 26.5% total 30% total 32% total

19. Incidence of allergic diseases (U.S.A.)

22. Diagnosis Of Allergic Diseases

23. Incidence of Allergic Disorders in UAE 1994 28% 14% % % %

24. Hygiene theory and TH development

25. Types of Allergy Tests Non Specific : Eosinophils Count Total Serum Ig E Abs. Specific tests: 1- Skin Prick Tests 2- Rast Specific IgE Abs. 3- Patch Skin Test Common 4- Measurement of mediators levels E.C.P , Tryptase , Histamine 5- Provocation & Challenge Test 6- Exhaled nitric oxide test ? Alternative Tests ?? Advanced

30. (SPT ) Procedure A sterile special prick lancet is used to make a small prick through the drop and a new lancet is used for each allergen used. After this, the excess allergen is removed by laying a tissue on the arm (not by wiping).

31. Skin Prick Test The test is then read at 15 minutes. Positive wheals are those which are 3mm or more in diameter greater than the negative control.

34. Rast IgE Procedure Step 1: The specific allergen is bound to a solid-phase support Step 2: Patient serum is incubated with the solid phase material, allowing reaction of the specific IgE with the allergen. Excess serum and non-allergen specific IgE are then washed away. Step 3: Labeled anti-IgE antibody conjugate is added. A subsequent wash removes unbound labeled antibody. Step 4 Measurement of the bound labeled anti-IgE by the proper detector is directly proportional to the patient's allergen specific IgE e e

35. RAST IgE TEST

37. Patch Skin Test Contact allergens ready coupled to tape Contact allergens manually prepared

38. Patch Skin Testing 48 – 72 hrs later the patch is removed and the skin sites are assessed for allergic or eczematous changes

39. Patch Test Result If the patients is allergic to the tested material , his T CD8 lymphocytes are sensitized and the contact allergen will cause them to secrete certain cytokines that attract inflamatory cells to the site and produce the positive reaction manifested by erythema, papules and vesicles. It is a Delayed Hypersensitivity (Type 4) reaction

42. ECP Test Step 1: Anti-ECP Coupled to a solid phase (immunoCAP). Step 2: Patient serum is added and the ECP will bind the anti-ECP immunoCAP. Step 3: Tracer anti-ECP antibody conjugate is added. Step 4: Measurement of the bound labeled anti-ECP by the proper detector is directly proportional to the patient's serum ECP. e e

43. Patch Skin Test Contact allergens ready coupled to tape Contact allergens manually prepared

44. Patch Skin Testing 48 – 72 hrs later the patch is removed and the skin sites are assessed for allergic or eczematous changes

45. Patch Test Result If the patients is allergic to the tested material , his T CD8 lymphocytes are sensitized and the contact allergen will cause them to secrete certain cytokines that attract inflamatory cells to the site and produce the positive reaction manifested by erythema, papules and vesicles. It is a Delayed Hypersensitivity (Type 4) reaction

48. ECP Test Step 1: Anti-ECP Coupled to a solid phase (immunoCAP). Step 2: Patient serum is added and the ECP will bind the anti-ECP immunoCAP. Step 3: Tracer anti-ECP antibody conjugate is added. Step 4: Measurement of the bound labeled anti-ECP by the proper detector is directly proportional to the patient's serum ECP. e e

49. ECP Test Step 1: Anti-ECP Coupled to a solid phase (immunoCAP). Step 2: Patient serum is added and the ECP will bind the anti-ECP immunoCAP. Step 3: Tracer anti-ECP antibody conjugate is added. Step 4: Measurement of the bound labeled anti-ECP by the proper detector is directly proportional to the patient's serum ECP. e e

50. Tryptase Assay Mast cells release a unique tryptase enzyme upon activation. The presence of measurable serum tryptase is a good index of mast cell activation, especially in cases of anaphylaxis where Tryptase Level increases sharply within half an hour and remains high for about 6-20 hours. Clotted blood samples should be taken serially after a suspected anaphylactoid reaction at ½ - 1 hour intervals for 4-6 hours after the reaction and serum stored for mast cell tryptase assay .

52. Challenge Test Food For a suspected food allergy we can perform the Double Blind Placebo Controlled Food Challenge (DBPCFC) Test. In this test, the offending food is concealed in a capsule or broth and under careful supervision is given to the patient, starting with very small dose and increasing it gradually to see if he reacts to it. This should only be done in specializede allergy clinics with full resuscitation equipment available. This is the most accurate food allergy test but it is time consuming.

53. Histamine Challenge Test This test depends on the fact that inhalation of histamine or methacholine provokes Bronchospasm in most asthmatic patients. Increasing histamine concentration are inhaled until FEV 1 drops by 20% and the concentration causing this fall (PC20) is recorded and compared with the normal

54. Exhaled Nitric Oxide Test

55. Controversial Allergy Tests Some practitioners perform tests that have not been shown to have an acceptable degree of diagnostic reliability or reproducibility on repeated testing. These tests should therefore not be relied upon for allergy diagnostic purposes as they are of an inferior nature and regarded as a cheating practice.