Diagnostica molecolare nell allergia alimentare

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Fabia Lamberti
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1 Diagnostica molecolare nell allergia alimentare Filippo Fassio SOD Immunologia e Terapie Cellulari Direttore Prof. E. Maggi

2 Diagnostica allergologica: evoluzione

3 La diagnosi di allergia alimentare The history of an immediate reaction consisting of typical allergic symptoms within 2 h of ingestion, supported by positive tests for specific IgE antibodies, is usually sufficient to establish a presumptive diagnosis for suspected IgE-mediated reactions.

supported by positive tests for specific IgE antibodies, is usually

4 La diagnosi di allergia alimentare

5 Limiti dei test diagnostici The fact that many foods are usually consumed at the same time, may obscure identification of the triggering allergen. Higher concentrations of food-specific IgE and larger skin test wheals correlate with an increased likelihood of a reaction upon ingestion. Unfortunately, these tests are not sufficiently sensitive or specific to establish a diagnosis without supporting evidence. Therefore, in the diagnosis of food allergy a convincing history of reaction is the key but only a well-performed OFC can give a definitive diagnosis. ORAL FOOD CHALLENGE

Unfortunately, these tests are not sufficiently sensitive or specific to establish a diagnosis without supporting evidence.

6 Limiti dei test diagnostici «Tali risultati sono però influenzati da molteplici variabili e sono stati validati su popolazioni non europee. La loro riproducibilità nella popolazione italiana èquantomeno da confermare».

7 Limiti dei test diagnostici

8 Allergia o sensibilizzazione? 1. Unfortunately, the serum or skin test results are not accurately predictive of the nature or severity of reaction to the particular allergen. 2. It is well established that the presence of food-specific IgE (i.e. sensitization) is not intrinsically diagnostic of food allergy. 3. Several studies have demonstrated that less than 40% of patients with positive PSTs or food specific IgE have OFCproven food allergy 4. Additionally, reactions may occur in patients with negative test results presumably because the test may be missing some essential proteins or epitopes

It is well established that the presence of food-specific IgE (i.e. sensitization) is not intrinsically diagnostic of food allergy. 3.

9 Allergia o sensibilizzazione? Component resolved diagnostics may provide a diagnostic and prognostic platform for differentiating subjects with food allergy from those with sensitization based on crossreactivity, for prediction of severityof reactions based on sensitization to proteins with greater risk of severe reactions, and prediction of natural history

differentiating subjects with food allergy from those with sensitization based on

10 Allergia o sensibilizzazione? Component resolved diagnostics may provide a diagnostic and prognostic platform for differentiating subjects with food allergy from those with sensitization based on crossreactivity, for prediction of severity of reactionsbased on sensitization to proteins with greater risk of severe reactions, and prediction of natural history

11 Allergen component-resolved testing might help to identify patients sensitized to food, latex, or venom who are at increased risk of anaphylaxis after exposure to these allergens versus those who are sensitized but clinically tolerant to these allergens

increased risk of anaphylaxis after exposure to these allergens

13 Allergia all Arachide BMJ 2008:337;a2880

14 Allergia all Arachide Dei 91 bambini sensibilizzati all arachide, allergia confermata in 19 casi (21%) JACI 2010; 125: 191

15 Allergia all Arachide JACI 2010; 125: 191 Una valutazione allergologica con approccio CRD, può aiutare ad identificare i veri allergici?

16 Allergia all Arachide La differenza piùmarcata tra sensibilizzati ed allergici èevidenziata dalla risposta ad Ara h2

17 Allergia all Arachide

18 Allergia all Arachide JACI 2009;124(4):771-8.e5

19 Allergia all Arachide differenze geografiche Ara h 2 Ara h 9

20 Allergia a frutta e verdura fresca

21 Allergia al kiwi It is nowadays among top ten food allergy sources in Europe Kiwifruit allergy can be due to monosensitization or associated with pollen (grass, birch) or latex allergy

22 Allergia al kiwi The papain-like cysteine protease, actinidin(act d 1), represents a major allergen and is also abundantly expressed (up to 50% of soluble protein fraction) This highly active protease may also account for the rapid degradation of other proteins including allergens, which in turn affects the varying quality of test solutions for Skin Prick Tests (SPTs) The diagnostic sensitivity of the extract ImmunoCAP was 17% compared with 77% when taking all the individual allergen tests together

23 Allergia al kiwi sensitization to Act d 1 and Act d 3 was significantly linked with anaphylactic reactionsin the patients Sensitization to Act d 2, Act d 8 and Act d 11 increased the specificity of the test Act d 7 and Act d 9 reactivity decreased specificity

24 Allergia al kiwi sensitization to Hev b 11, the latex chitinase, was predominantly found in the kiwifruit latex allergic patients, thus representing a marker for the latex kiwifruit syndrome in all these recent studies sera were identified that did not display IgE directed to any of the allergens tested so far and it may well be that the panel of kiwifruit allergens awaits completion Kiwi gold: Act d 1 (circa 50 volte meno)

25 Allergia al pomodoro In Germany 9% among birch pollen allergic patients reported tomato-induced allergic symptoms As a result of the potential of tomatoes to induce unspecific histamine liberation the allergenic properties of that vegetable have been mainly neglected in the past In a Spanish investigation only 16% of tomato-sensitized patients reported symptoms upon tomato ingestion

26 Allergia al pomodoro 45% of tomato allergic patients reacted to LTP 65% to a protein suspected to be profilin 15% of patients recognized only the LTP and experienced more severe symptoms to tomato

27 Allergia al pomodoro Tomato seeds are rich in proteins and constitute 70% storage protein such as globulins Recently, a legumin and a vicilin were identified as putative tomato seed allergens

28 Allergia al pomodoro In summary, tomato is a complex allergenic vegetable and the reliability of the single allergens for molecular diagnosis has to be confirmed in future studies

29 Allergia alla nocciola Dosaggio IgE totali (RIST): 37 ku/l Dosaggio IgE specifiche per inalanti: tutte < 0.10 kui/l Dosaggio IgE specifiche per alimenti: Nocciola 3,07 kui/l Noce 0,12 kui/l Il prick test èrisultato positivo per: Nocciola (+++) Noce(+/-) Pinolo (+/-)

30 Allergia alla nocciola Negativo!

31 Allergia alla nocciola

32 Microarray 112 allergeni (Thermo Fisher) 103 allergeni (Phadia) 89 allergeni (VBC genomics) ma in natura ce ne sono DI PIU

33 Non conta solo la quantità! Allergeni (103)

34 Conclusioni Niente panico, ma individuare i soggetti che possono piùfacilmente avere reazioni gravi! Gli allergeni molecolari possono aiutare a stratificare il rischio, ma attenzione alle differenze geografiche! (anche nello studio della letteratura)

35 Conclusioni Ci sono alimenti per i quali (come CRD) siamo più avanti ma non cosìtanto! Per altri alimenti (anche importanti) siamo più indietro Ci possiamo accontentare di 4 molecole per 2 alimenti? (il pomodoro ed i suoi semi)

36 Microarray 112 allergeni (Thermo Fisher) 103 allergeni (Phadia) 89 allergeni (VBC genomics) Allergeni (103)

37 Conclusioni

38 Conclusioni

39 Allergome in caso di bisogno

41 Possiamo fermarci qui? Grazie!

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