These type of scenarios are always tough - when patients present with subjective symptoms but no objective data to support or refute their symptoms. If I understand your question correctly she had a tortilla that contained spelt, wheat, millet, sesame seeds, lentil and barley. It is not clear to me from the data presented if this was all she ate - meaning what was inside the taco: beef, chicken, fish etc. For the purposes of this discussion I am going to assume no other foods were consumed or if they were consumed they have been ruled out as possibly etiologic for her symptoms. If the patient has eaten wheat and lentil since the episode and had no symptoms then these would seem to be less likely culprits to have caused the sensation she had. It would be reasonable to assume that sesame seeds, spelt, barley and millet could still be potential triggers and these should be evaluated for either through skin testing or specific IgE testing. I have looked on Pharmacia website and all these are available for specific IgE testing.
With regards to cross reactivity, we have asked Dr David Fleischer for his thoughts:
“There is controversy over the role of cross-reactive allergens among wheat and barley - both in IgE-mediated reactions and in non-IgE (EoE, celiac). Barley and wheat obviously contain gluten but likely other cross reactive proteins. Studies show a variability in clinical reactivity between wheat and barley, as high as 55% in a study by Pourpak et al. in 2005 in IgE-mediated reactivity. I would consider spelt in this same realm as it contains gluten, but there are some patients with IgE-mediated allergy who can consume spelt without reaction, while celiac patients are recommended to avoid spelt since it contains gluten.
As for millet, it does not contain gluten, but in one study (attached) there was cross-reactivity noted with rice and wheat. These patients had IgE mediated allergy to millet, but their primary sensitization occurred through the respiratory route due to bird-keeping and exposure to millet-contained birdseed.
I do not know the remainder of this history - how old the patient is; does she have allergic rhinitis and allergy to grass, thus possible cross-reactivity with grains; does she have OAS with other foods? Nor do I know the results of any testing that has been done.
Given the information above, and the fact that she has eaten wheat since without reactions, it sounds reasonable to test the other foods she has not re-eaten, with the caveat that results could be positive due to grass allergy (if she has it) or some cross-reactivity among the grains. The ultimate test, though (and my recommendation), would be to perform graded food challenges to these other foods to prove clinical reactivity or not to them. Since there were only subjective symptoms, I would consider doing these in some blinded fashion (single blinded)) with placebo doses to help sort out the subjectivity.”
Hemmer W et al, Food Allergy to millet and cross reactivity with rice, corn and other cereals. Allergology International 2016
We hope this has been helpful.
Andrew Murphy MD, FAAAAI