The use of components in allergy diagnostics. Dr. Sc. E. Van Hoeyveld Laboratory Medicine

Transcription

1 The use of components in allergy diagnostics Dr. Sc. Laboratory Medicine

2 Use of components in the clinic Basics of allergen components and their clinical implications I. Allergen component names II. Properties Structure / protein family Protein family / protein stability

3 Use of components in the clinic t3: Betula verucosa g6: Phleum pratense d1: Dermato. pteronys. e1: Felis domesticus f13 : Arachis hypogaea Bet v 1, 2, 4, 6, 7 Phl p 1,..5, 7 12 Der p 1, 2, 3,.10,.. Fel d 1, 2, 3 Ara h 1, 2, 3,..8, Preceded by: r : recombinant protein rbet v 1 n : natural purified protein nder p1

4 Use of components in the clinic Basics of allergen components and their clinical implications I. Allergen component names II. Properties Structure / protein family Protein family / protein stability

5 Use of components in the clinic II. Properties of allergen components Structure Abs bind only to allergen components of that particular species Patients with reactivity to these components are suited for IT

6 Use of components in the clinic II. Properties of allergen components Structure / protein family similar structures in different species, biologically related or unrelated causing cross-reactivity between related/unrelated species

7 Use of components in the clinic II. Properties of allergen components protein family/stability: heat and digestion labile, milder / local symptoms resistant to heat and/or enzymatic digestion, severe clinical reactions

8 Allergens of plant origin and vegetable foods Protein family/ function Characteristics Source Allergens Cross-reactivity Clinical symptoms Storage proteins Source material during growth. Often stable, heat resistant hazel peanut soy bean wheat nsltp stable to heat, digestion mugwort hazel peanut peach Cor a 9 Ara h 1, 2, 3 Gly m 5, m 6 Tri a 19 Art v 3 Cor a 8 Ara h 9 Pru p 3 none pollen and vegetable foods - moderate to severe - also reactions to cooked foods - systemic and severe reactions in addition to OAS - reactions to cooked foods Bet v 1 superfamily Calciumbinding proteins Profilin CCD PR-10 proteins. Major birch pollen allergen. Heat labile. e.g. in grass-weed-tree pollen, not in vegetable foods Actin-binding protein. e.g. in birch, grasses, peach, latex Marker for sensitization to carbohydrate determinants e.g. in pollen, Hymenoptera birch hazel peach kiwi peanut soy bean grasses birch grasses birch peach latex Bet v 1 Cor a 1 Pru p 1 Act d 8 Ara h 8 Gly m 4 Phl p 7 Bet v 4 Phl p 12 Bet v 2 Pru p 4 Hev b 8 Bromeline Mux f3 pollen and vegetable foods Pollen (pollen polysensibilisatie) pollen, pollen plants, vegetable foods Pollen, insects Local symptoms (OAS) rare rare none

9 Mugwort extract (Artemisia vulgaris) IgE-mediated mugwort allergy confirmed clinically relevant mugwort allergy unlikely component-resolved diagnostics major mugwort allergen: n Art v 1 Cross-reactive mugwort allergen r Art v 3 heat labile ns LTP heat-stable mugwort specific limited cross-reactivity with other LTPs Pru p 3 (peach) Cor a 8 (hazel) Suitability for IT nart v 1: + nart v 1: + nart v 1: - rart v 3: - rart v 3: + rart v 3: +/- high medium low

10 Timothy grass pollen extract (Phleum pratense) IgE-mediated grass pollen allergy confirmed Clinically relevant grass pollen allergy unlikely Component-resolved diagnostics Major timothy grass pollen allergen: rphl p 1, rphl p 5 Cross-reactive minor timothy grass pollen allergens: rphl p 7, Phl p 12 Grass pollen specific Ca-binding protein Profilin present Grass pollen Pollen from grasses, trees, weeds pollen from fruits, latex symptoms Suitability for grass pollen specific immunotherapy local symptoms OAS to grass pollen rare rare rphl p 1, 5: + rphl p 1, 5: + rphl p 1, 5: - rphl p 7, 12: - rphl p 7, 12: + rphl p 7, 12: +/- HIGH MEDIUM LOW

11 Birch pollen extract (Betula verrucosa) IgE-mediated birch pollen allergy confirmed Clinically relevant birch pollen allergy unlikely Component-resolved diagnostics Major birch pollen allergen: rbet v 1 Cross-reactive minor birch pollen allergens: rbet v 2, rbet v 4 PR-IO protein (heat labile) profilin Ca-binding protein present hazel, Rosaceae, fruits, peanut, soy bean pollen, fruits, latex pollen from grasses, trees, weeds symptoms local symptoms OAS rare rare Suitability for birch pollenspecific immunotherapy rbet v1: + rbet v 1: + rbet v 1: - rbet v 2, 4: - rbet v 2, 4: + rbet v 2, 4: +/- HIGH MEDIUM LOW

12 CCD test Useful: 1. sensitization to foods of plant origin 2. sensitization to latex in a pollenallergic patient without occupational risk 3. subjects testing positive for both honeybee and wasp venom

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14 Hazelnut + Cor a 8 Hazelnut: neg Cor a 8: neg Hazelnut: pos Cor a 8: neg Hazelnut: pos Cor a 8: pos Very low risk for severe reactions to hazelnut Risk for severe reactions to hazelnut High risk for severe reactions to hazelnut Also to cooked food Recommendations for further testing: Cor a 1 CCD risk grading

15 Better differentiation of the peanut allergic patient Today, five peanut components are available; Ara h 1, Ara h 2, Ara h 3, Ara h 8 and Ara h 9. The presence of Specific IgE to Ara h 1, Ara h 2 and Ara h 3 is indicative of a true peanut allergy 1-3 Patients with true peanut allergy often have antibodies to Ara h 2. However, in rare cases sensitization to only Ara h 1 and/or Ara h 3 can occur 4 Sensitization to the cross-reactive allergen components Ara h 8 and Ara h 9 (present in pollen and plant foods) varies depending on local exposure Mittag D et al. J Allergy Clin Immunol 2004;114: Astier C. et al. J Allergy Clin Immunol 2006; 118: Flinterman AE. Et al. Clin Exp Allergy 2007; 37(8): Peeters KABM et al. Clin Exp Allergy 2007;37(1): Codreanu et al. Int.Arch.Allergy.Immunol 2011;154: Lauer I. et al. Clin Exp Allergy 2009;39: Krause S. et al. J Allergy Clin Immunol 2009;124:

16 Conclusion All available peanut components are needed for a complete risk assessment of a suspected peanut allergy Sensitization to several peanut components is a stronger indication of more severe reactions than sensitization to only one of the components

17 Allergens of animal origin and animal foods Protein family/ function Characteristics source Allergens Cross-reactivity Clinical symptoms Serum albumins Common proteins in different biological fluids and solids cow Bos d 6 cow s milk, meat and dander of mammals food reactions to raw meat, milk, OAS to dander parvalbumins stable to heat, digestion major allergen in fish cat dog cod fish carp Fel d 2 Can f 3 Gad c 1 Cyp c 1 alb from dog, horse, pig, cow alb from cat, horse, pig, cow different species of fish amphibians food reactions, OAS severe reactions, OAS reactions to cooked foods tropomyosins lipocalins Actin-binding proteins in muscle fibres Stable, important allergens in animals house mite shrimp cockroach cat dog Der p 10 Pen a 1 Fel d 1 Can f 1, Can f 2 mites, crustaceae, molluscs rare severe reactions, OAS OAS

18 Felis domesticus (cat) Source material: Epithelium and dander rfel d 1: major cat allergen, species-specific Cat serum albumin (nfel d 2) Cross reaction with other mammal albumins (e.g. dander from dog, horse, pig, cow) Can cause reactions eating pork, beef.

19 Canis familiaris (dog) Source material: Epithelium and dander Can f 1 Can f 2 major allergens, salivary lipocalins Can f 3 dog serum albumin: - cross reaction with other mammal albumins e.g. cat Fel d 2 - sensitization only to Can f 3: primary sensitizer needs to be identified (Can f 4) (Can f 5)

20 Parvalbumin: (rcyp c 1),rGad c 1 rcyp c 1: Parvalbumin from Carp rgad c 1: Parvalbumin from Cod Parvalbumins are abundant and stable allergens. Parvalbumins are small (12-kDa) proteins with a remarkable resistance to heat, denaturing chemicals, and proteolytic enzymes. sensitizing agents for > 95% of fish allergic patients

21 Mite extract tropomyosin A possible decision tree for Der p-immunotherapy. Serological testing with mite allergen extracts (Der p, Der f, ) confirms IgE-mediated allergy. Component resolved diagnosis (CRD) with major (Der p 1, Der p2) and cross-reactive (Der p 10) allergens may be performed to further determine suitability for Der p-specific immunotherapy. Adapted from: G. Pittner et al., Clinical and Experimental Allergy, 2004; 34:

22 Established immunological relations within invertebrates: o Crustaceans: e.g. shrimp, crab, crawfish, lobster o Mollusks: e.g. clams, mussels, oysters, snails, squid o Arachnids: e.g. mites, spiders o Insects: e.g. cockroaches Reese G et al. Immunol 1999;119:247-58

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24 Conclusion Determination of IgE antibodies to components: reveals allergens to which the patients is sensitized detects primary (species specific) allergens detects markers of crossreactivity marker to evaluate risk of severe reactions future: tool for adapting treatment strategy