Q:

5/14/2013
A patient with positive ST to avocado can eat cooked avocado but not raw avocado. Does heat denature the avocado protein?

A:

Thank you for your inquiry.

You did not specify the type of reaction your patient experiences upon the ingestion of raw avocado. Of particular importance is that you did not mention whether this was a simple oral allergy syndrome or a systemic reaction. Obviously, if it was an oral allergy syndrome, like most such reactions, heating the food in question will destroy the allergens which are both heat and acid labile. This is also the case in some systemic reactions as well. I would assume that you are speaking of a systemic reaction.

I believe the demonstration that she can eat cooked avocado clearly points to the fact that heat does destroy the allergen in her case, and this would not be unexpected since the major allergen in avocado is Pers a 1. Pers a 1 is a class 1 chitinase. It is a 32 kDa heat-labile protein. Cooking would destroy it. Pers a 1 is also extensively degraded by gastric juice, but the resulting peptides can exhibit IgE-binding both in vivo and in vitro (1).

In summary, I believe that your patient is reacting to a heat-labile allergen in avocado, perhaps Pers a 1.

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

Reference:
1. Diaz-Perales A, Blanco C, Sanchez-Monge R, Varela J, Carrillo T, Salcedo G. Analysis of avocado allergen (Prs a 1) IgE-binding peptides generated by simulated gastric fluid digestion. J Allergy Clin Immunol 2003;112(5):1002-7.

Sincerely,
Phil Lieberman, M.D.

AAAAI - American Academy of Allergy Asthma & Immunology