Q:

4/5/2012
I have a patient with latex-fruit allergy. She posed a question to which I can't find an answer. With latex-fruit allergy, are the cross-reacting antigens in fruits/vegetables/nuts denatured by cooking, thereby allowing asymptomatic ingestion, as they are in pollen-food syndrome? In other words, does she have to avoid the foods if cooked? Her only reaction so far is with banana, and she was wondering about eating banana bread. Thank you.

A:

Thank you for your inquiry.

Unfortunately the answer to your question is not known, and in actuality depends upon the allergen in the food or foods responsible for the cross-reactivity. In many instances, latex-fruit syndrome is produced by heat and acid labile antigens, and these would be very unlikely of course to produce an anaphylactic event if the food was heated. However, even in the oral allergy syndrome (fruit-pollen allergy), in rare instances anaphylactic episodes have been recorded to the ingestion of fruits which previously produced only oral symptoms.

In addition, patients who are allergic to latex may have allergens to heat stable as well as heat labile allergens within a food, and this sensitivity may be independent of any cross-reactivity between latex allergens and food allergens per se since atopic individuals, as you know, are prone to make IgE antibodies against multiple allergens.

To illustrate this concept, since banana is the food in question, we can use it as an example.

Bananas contain both heat labile and heat stable allergens that can cross-react with latex. A Class 1 chitinase, which is heat stable and which shares a hevein-related structure found in latex, can also be found in banana (as well as avocado and chestnut). This antigen is stable and heat resistant. If your patient has cross-reactivity between latex and banana based upon sensitivity to this antigen, she may well react to banana nut bread. In fact, banana is a very complex allergen and there are at least five well-defined allergenic moieties excluding the above mentioned chitinase. In a study of latex-allergic patients, 16 allergenic components were identified in banana. These allergens have molecular weights ranging from 17 to 128 kDa. Two of these were major allergens. One was of 33 kDa protein that was detected in 15 of 19 sera (88%), and there was also a 37 kDa detected in 13 of 19 sera (1). The 33 kDa allergen exhibited features of a chitinase which is a Class 1 antigen, and it had the hevein-like domain and, as noted, was a major allergen. It would be expected to be heat stable.

When one looks at the sera from latex-allergic individuals, 45% recognized 14 allergens in banana, and skin reactivity was found in 14 of 18 latex-allergic patients studied (2).

Thus we can see that the cross-reactivity between latex and banana can be related to a number of different allergens, some of which are heat stable and some of which are heat labile. Without component testing, we cannot tell in a given patient which allergens are responsible for the cross-reactivity.

Complicating this scenario is the fact that some individuals who initially expressed only oral allergy symptoms to banana can later experience anaphylaxis.

In summary, the majority of fruit and vegetable allergens cross-reacting with latex are probably heat labile, but there is always the possibility of cross-reacting with a heat stable allergen, and finally that there may be simultaneous allergy to non-cross-reacting antigens. Thus, if your patient has experienced a problem with uncooked banana, the only way to tell with a reasonable degree of certainty whether she might react to banana bread would be to do a graded oral food challenge.

Thank you again for your inquiry and we hope this response is helpful to you.

1) Delbourg MF, Guilloux L, Moneret-Vautrin DA, Ville G. Hypersensitivity to banana in latex-allergic patients. Identification of two major banana allergens of 33 and 37 kD. Ann Allergy Asthma Immunol 1996;76(4):321-6.

2) Alenius H, Makinen-Kiljunen S, Ahlroth M, Turjanmaa K, Reunala T, Palosuo T. Crossreactivity between allergens in natural rubber latex and banana studied by immunoblot inhibition. Clin Exp Allergy 1996;26(3):341-8.

Sincerely,
Phil Lieberman, M.D.

AAAAI - American Academy of Allergy Asthma & Immunology