Oral Allergy Syndrome (OAS)

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Jan Hed, Clin Immunologist, MD, PhD
Karolinska Institutet, IMPI, Div of Clin Immunology
Huddinge University Hospital, Sweden
 
The statements below are based on conclusions from selected publications. Their intention is to highlight recent research and information that could be beneficial in allergy in vitro testing. They can include seemingly contradictory statements due to differences in selecting patient populations as well as in the study design.
  • Oral Allergy Syndrome (OAS) is a form of contact urticaria that occurs minutes after ingesting certain foods to which the patient is previously sensitized. Symptoms are confined to the lips and oropharynx and, by definition, do not involve other target organs (see ref. 1 for review).
     
  • OAS is the second most common symptom in IgE-mediated food hypersensitivity among adults; the order is urticaria/angioedema (70%), oral allergy syndrome (54%), asthma (37%) and anaphylaxis (27.5%) (2).
     
  • OAS is often seen in patients with allergic pollenosis due to cross-reactivity between pollen and various fruits and vegetables, i.e. the cross-reactivity of apple, carrot, pear or cherry with birch pollen, and of tomato, melon or watermelon with grass pollen (3).
     
  • OAS has also been described for other food antigens such as shellfish (4) and chicken meat (5, 6). 
     
  • Birch-specific IgE levels heavily influence the onset of OAS, and probably play a critical role in the development of allergies to distinct vegetable foods (7).
     
  • OAS is associated with more severe respiratory symptoms and with higher birch-specific and total IgE levels (8,9); moreover, its onset is clearly related to the duration of birch pollinosis (8).
     
  • Patients who develop Apiaceae sensitivity (carrot, celery and fennel) had much higher birch-specific IgE levels than patients who developed apple/hazelnut allergy only (7).
     
  • 15% of patients with birch pollen hypersensitivity are not prone to OAS, which suggests that their anti-birch IgE might be directed against determinants that do not cross-react with food allergens (8).
     
  • Clinical cross-reactivity to Prunoideae (peach, cherry, apricot and plum) in an Italian study was essentially due to a common IgE-binding major allergen that did not share specificity with grass and birch pollen (10).
     
  • The foods that most often provoked OAS in Japan were, in order of frequency, melon, kiwi, crab and shrimp (4).

References:

    1. Sampson HA. Food allergy. In: Kay AB, editor. Allergy and Allergic Diseases. Blackwell Science Ltd. 1997:1517-49.
    2. Castillo R, Delgado J, Quiralte J, Blanco C, Carrillo T. Food hypersensitivity among adult patients: epidemiological and clinical aspects. Allergol Immunopathol (Madr) 1996; 24:93-7.
    3. Ortolani C, Ispano M, Pastorello E, Bigi A, Ansaloni R. The oral allergy syndrome. Ann Allergy 1988; 61:47-52.
    4. Arai Y, Ogawa C, Ohtomo M, Santo Y, Ito K. (Food and food additives hypersensitivity in adult asthmatics. II. Oral allergy syndrome in adults asthmatic with or without Japanese cedar hay fever). Arerugi 1998; 47:715-9.
    5. Vila L, Barbarin E, Sanz ML. Chicken meat induced oral allergy syndrome: a case report. Ann Allergy Asthma Immunol 1998; 80:195-6.
    6. Escribano MM, Serrano P, Munoz-Bellido FJ, de la Calle A, Conde J. Oral allergy syndrome to bird meat associated with egg intolerance. Allergy 1998; 53:903-4.
    7. Asero R. Relevance of pollen-specific IgE levels to the development of Apiaceae hypersensitivity in patients with birch pollen allergy. Allergy 1997; 52:560-4.
    8. Asero R, Massironi F, Velati C. Detection of prognostic factors for oral syndrome in patients with birch pollen hypersensitivity. J Allergy Clin Immunol 1996; 97:611-6.
    9. Gall H, Kalveram KJ, Forck G, Sterry W. Kiwi fruit allergy: a new birch pollen-associated food allergy. J Allergy Clin Immunol 1994; 94:70-6.
    10. Pastorello EA, Ortolani C, Farioli L, Pravettoni V, Ispano M, Borgå Å et al. Allergenic cross-reactivity among peach, apricot, plum, and cherry in patients with oral allergy syndrome: an in vivo and in vitro study. J Allergy Clin Immunol 1994; 94:699-707.