D3.227 - Millet as a Rare Allergenic Source: A Case Study of Systemic Allergic Reactions
Background
Millet (Panicum miliaceum), a gluten-free cereal, is increasingly included in health foods but is a rare allergen. The allergens of this seed have not been clearly identified, and cross-reactivity with other cereals is controversial or unclear. This study investigates the allergenic potential of millet in a patient who experienced a systemic allergic reaction following its ingestion.
Method
A 45-year-old woman with a history of rice allergy and dust mite-related rhinitis presented with facial erythema, respiratory distress, and urticaria 30 minutes after consuming a cereal bar containing millet, rice flour, and other seeds. She tolerated other cereals, legumes, and nuts but avoided eating rice. The patient had previously kept canaries and parakeets and reported ocular itching and nasal congestion when feeding them (with a birdseed containing millet) or cleaning the cage, attributing these symptoms to her dust mite allergy.
Results
Skin prick tests (prick-by-prick) confirmed sensitization to cooked rice but not to other components of the cereal bar, LTP (peach), and profilin. Specific IgE (CAP) testing was positive for millet (1.45 kU/L) and rice (0.61 kU/L) but negative for soy, mustard, flaxseed, rye, wheat, sesame, Pru p 4, Tri a14, and Tri a 19. IgE-Western blot analysis revealed strong binding to two proteins in millet extracts: a 10 kDa band and another smaller band below 10 kDa. No Ig E reactivity with rice proteins was observed.
Conclusion
This case identifies millet as a potential allergenic food source, with nsLTPs possibly playing a role in its allergenicity, although Pru p 3 and Tri a 14 were negative. Additionally, no cross-reactivity with rice proteins was observed, reinforcing the hypothesis that millet acts as an independent allergen.
Comprehensive allergenic profiling is crucial to identifying specific triggers and providing dietary recommendations for sensitized individuals, especially as millet becomes more common in gluten-free diets.
