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Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
Diagnoisis of allergy in children
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Diagnoisis of allergy in children

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  • 1. DIAGNOISIS OF ALLERGY IN CHILDREN <ul><li>Allergic disorders are the commonest chronic diseases of childhood. Their prevalence has greatly increased during the last decades reaching around 30% of children all over the world and causing a major public health problem all over the world </li></ul>
  • 2. LEARNING OBJECTIVES <ul><li>Discuss the significance of allergy tests for laboratory personnel & physicians </li></ul><ul><li>Describe the various in vivo and in vitro allergy diagnostic tests in children </li></ul>2) 3) Define the difference in the laboratory findings between patients with asthma and with other pulmonary obstructive diseases under different circumstances.
  • 3. Significance To Lab. <ul><li>The current medical practice allows patient to be seen initially by a primary care physician(G.P.), who must decide to manage that patient within his clinic or seek a referral to an allergy specialist for further evaluation. In this paradigm, laboratory tests that establish a high likelihood of allergic disease take on increased importance, and pathologists have an important role as consultants to nonallergist physicians, many of whom have limited knowledge about these laboratory tests. </li></ul>
  • 4. “ The Allergy March” <ul><li>In genetically predisposed infants, eczema (atopic dermatitis) is often the first manifestation of allergic disease. A pruritic rash that involves the cheeks, neck, chest, and the extensor surfaces of the arms and legs characterizes this disease. Atopic infants and children younger than 3 years of age may also have gastrointestinal symptoms (colic, diarrhea, vomiting, and abdominal pain) or suffer from chronic otitis. Less commonly, children younger than 3 years may already suffer from recurrent wheezing. As the atopic child matures, cutaneous and gastrointestinal symptoms often give way to worsening respiratory symptoms with development of allergic rhinitis and asthma. The entire sequence of the allergy march is shown schematically </li></ul>
  • 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:
  • 8. Incidence of Allergic Diseases <ul><li>Over all Range :15- 30% </li></ul><ul><li>Allergic Rhinitis : 20-30 % </li></ul><ul><li>Eczema And Urticaria: 15-25% </li></ul><ul><li>Asthma: 5-15% </li></ul><ul><li>Other allergic diseases : 5- 20% </li></ul>
  • 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
  • 12.  
  • 13. Atopic and Contact Eczema Atopic Eczema : Type I & Type 4 hypersensitivity reactions
  • 14. Anphylaxis
  • 15. Food Allergy diagnosis <ul><li>The first step in addressing possible food allergies in a child is : History/Physical: The parent will have to have a history of the disorder including symptoms, timing, reproducibility and whether the condition presents acute reactions or resembles a chronic disease. The parent should have diet details or a symptom diary listing specific causal food(s) and any possible &quot;hidden&quot; ingredient(s). This will be followed by a physical examination. </li></ul><ul><li>Diagnosis: If the condition is suspected of being IgE-mediated, then prick skin tests or RAST (or a fresh extract in the case of an oral allergy) will be performed. </li></ul><ul><li>Interpretation of Laboratory Tests: The positive prick test or RAST indicates the presence of the IgE antibody, not clinical reactivity (~50% false positive). A negative prick test or RAST essentially excludes IgE antibody (>95 percent). </li></ul><ul><li>When food-specific IgE concentrations predictive of clinical reactivity are present, then the following could be recommended: </li></ul><ul><li>Elimination diets eliminate suspected food(s), prescribe a limited &quot;eat only&quot; diet. This diet usually lasts between one and six weeks. </li></ul><ul><li>Oral challenge testing (physician supervised, with emergency medications available) can be open, single-blind, or double-blind, placebo-controlled. If the results indicate an IgE-mediated allergy, then the test for specific-IgE antibody could be negative (thus, reintroduce food) or positive (start the elimination diet). If the elimination diet provides no resolution, then reintroduce the food </li></ul>
  • 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.)
  • 20. Development of Allergic State <ul><li>Development of Allergic State depends on: </li></ul><ul><li>Environmental Factors: </li></ul><ul><li>Genetic Factors: </li></ul>
  • 21. Hygiene Hypothesis <ul><li>The increase in asthma and allergy rates over the past few decades in the developed world could be caused by the increasingly sterile world in which we live . </li></ul>
  • 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
  • 26. Types of Allergy Tests <ul><li>Estimation of Specific IgE in vivo & in Vitro </li></ul><ul><li>Assessment of inflammation by measurement of inflammatory markers in </li></ul><ul><ul><li>A- Airways based: </li></ul></ul><ul><ul><li>*. Exhaled air & Breathe Condensate </li></ul></ul><ul><ul><li>*. Induced sputum </li></ul></ul><ul><ul><ul><li>B : Non airways based </li></ul></ul></ul><ul><li>Blood & urine </li></ul>
  • 27. Skin Prick Test <ul><li>Skin Prick Test is the best test for immediate hypersensitivity as it provides useful confirmatory evidence for a diagnosis made on clinical grounds. </li></ul><ul><li>It is:- </li></ul><ul><li>Simple, </li></ul><ul><li>Quick, </li></ul><ul><li>Cheap, </li></ul><ul><li>Safe </li></ul><ul><li>method with a high degree of specificity and sensitivity. </li></ul>
  • 28. (SPT ) Procedure <ul><li>A positive (Histamine) and a negative (solvent ) should always be included. </li></ul><ul><li>The patient should not be on antihistamines prior to testing. </li></ul><ul><li>The test is done on a healthy skin on the inner aspect of the forearm or the back . The test area is marked with a marking pen according to the number of allergens to be tested. </li></ul><ul><li>Allergens are placed at 2cm apart using dropper from allergen vial. </li></ul>Pos. Neg. H G M F E
  • 29.  
  • 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.
  • 32. Skin Prick Test Measurement <ul><li>Wheal measurement compared with the old system </li></ul><ul><li>0+ = < 3 mm </li></ul><ul><li>2+ = 5-10 mm </li></ul><ul><li>3+ =10-15mm </li></ul><ul><li>4+ = > 15mm </li></ul><ul><li>A positive test is 2 mm or more greater than the negative control. However, a skin wheal 6mm or more across is more likely to be clinically relevant. </li></ul><ul><li>A wheal > 15 mm diameter suggests patient is very sensitive. </li></ul><ul><li>A wheal 10 to 15 mm diameter suggests patient is moderately sensitive </li></ul><ul><li>A wheal 5 to 6 mm diameter suggests patient is mildly sensitive. </li></ul>Neg Pos
  • 33. Specific IgE Test <ul><li>(Radio Allergo Sorbent Test) is an immunoassay to measure the specific IgE antibodies in patient's blood to certain allergens. </li></ul><ul><li>It depends on the same principles of ELIZA test. </li></ul><ul><li>Quality control reagents (calibrators, controls) should be always included and used to asses the quantity of patient's allergen specific IgE </li></ul>
  • 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
  • 36. Patch Skin Test <ul><li>Patch test is used for the diagnosis of delayed allergic reaction in the skin ( Allergic Contact eczema). </li></ul><ul><li>It involves the application of traces of various known contact allergens extracts { nickel, rubber, dyes, cosmetics, preservatives, medication } to the skin under adhesive tape and keeping them for 48 -72 hours </li></ul>
  • 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
  • 40. Patch Test Results Assessment <ul><li>Doubtful reaction ? </li></ul><ul><li>Faint macular or homogeneous </li></ul><ul><li>erythema, no infiltration </li></ul>Weak positive reaction + Erythema Infiltration Discrete papules Strong positive reaction +++ Erythema Infiltration Papules Discrete vesicles Extreme positive reaction Coalescing vesicles/bullous reaction ++++ Negative reaction --- Irritant reaction of different types *
  • 41. Eosinophils Eosinophils play an important role in allergic reaction . Their number is increased in blood and tissues.They are responsible for the late phase response when they are attracted to the site and cause an inflammatory response. They secrete many mediators; (MBP,ECP,EDN,EPO)& Cytokines. Serum Eosinophil Cationic Protein (ECP) is currently used for the monitoring of allergic inflammation in asthmatic patients and atopic eczema and to assess their activity and response to treatment. <ul><li>Mediators of Eosinophils: </li></ul><ul><li>Basic Proteins: (MBP,ECP,EDN, EPO). </li></ul><ul><li>Cytokines, </li></ul><ul><li>Chemokines </li></ul>
  • 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
  • 46. Patch Test Results Assessment <ul><li>Doubtful reaction ? </li></ul><ul><li>Faint macular or homogeneous </li></ul><ul><li>erythema, no infiltration </li></ul>Weak positive reaction + Erythema Infiltration Discrete papules Strong positive reaction +++ Erythema Infiltration Papules Discrete vesicles Extreme positive reaction Coalescing vesicles/bullous reaction ++++ Negative reaction --- Irritant reaction of different types *
  • 47. Eosinophils Eosinophils play an important role in allergic reaction . Their number is increased in blood and tissues.They are responsible for the late phase response when they are attracted to the site and cause an inflammatory response. They secrete many mediators; (MBP,ECP,EDN,EPO)& Cytokines. Serum Eosinophil Cationic Protein (ECP) is currently used for the monitoring of allergic inflammation in asthmatic patients and atopic eczema and to assess their activity and response to treatment. <ul><li>Mediators of Eosinophils: </li></ul><ul><li>Basic Proteins: (MBP,ECP,EDN, EPO). </li></ul><ul><li>Cytokines, </li></ul><ul><li>Chemokines </li></ul>
  • 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 .
  • 51. Provocation Tests <ul><li>In hospital, we can perform challenge (Provocation) tests by introducing the suspected allergen directly into the nose, lung or eye and measure to see if we can provoke an allergic reaction. This is primarily a research tool, but sometimes is needed. It should be done very carefully and under complete medical supervision. </li></ul>
  • 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.
  • 56. CONCLUSION <ul><li>Specific tests: </li></ul><ul><ul><ul><ul><ul><li>Skin Prick Tests </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Rast Specific IgE Abs </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Patch Skin Test </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Estimation of mediators (ECP, tryptase) </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Provocation tests </li></ul></ul></ul></ul></ul>Clinical Significance: 1- Confirm Diagnosis of Allergic Disease 2- Monitor response to traetment 3- Find the cause of that allergy <ul><li>Non Specific : </li></ul><ul><ul><ul><ul><ul><li>Eosinophils Count </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Total Serum Ig E Abs </li></ul></ul></ul></ul></ul>ALLERGY TESTS :
  • 57. <ul><li>Allergic diseases begin early in life, and the prevalence of allergic diseases is higher in children and adolescents by comparison with that in adults – rates are still increasing. Furthermore, asthma and related allergic and respiratory diseases constitute the commonest causes of morbidity in childhood with around 30% of primary care consutlations and 20% of hospital admissions. Immunologically driven diseases are common and of great importance in children. </li></ul>
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