Searching for hidden allergens in foodstuffs can be sometimes very complicated and challenging.
A non atopic girl, consulted in early 2013 by an episode of anaphylaxis with urticaria, angioedema, dyspnea, dysphagia and disphonia treated and solved with epinephrine. Over 2013 and 2014 patient suffered 4 similar episodes. Every single episode started 10-30 minutes after take some food.
Skin prick tests (SPT) with commercial extracts of every foodstuff involved in all episodes were all negative. Study of idiopathic anaphylaxis was also negative. Basal tryptase was 3.27μg/L (1-15.0).
Late 2014, patient suffered a new similar episode 10 minutes after taken some candies. Autoinjector of epinephrine was used by patient and was later assisted in Emergency Department. Tryptase after 120 minutes was 22.6μg/L.
Study in Allergy Office by prick-prick with candies was positive with reddish candies and negative with other colored ones. Specific IgE with carmine (ImmunoCap, Phadia, Sweden) was negative. Prick-prick with the insect Dactylopius coccus, collected from the cactus Opuntia coccinellifera, was positive.
A protein extract with cochineal and one with carminic acid were made. SPT with both extracts resulted positive and negative in 20 atopic controls. An IgE western-blot was performed. Two bands were recognized (16-18kDa, 38-40kDa) with the cochineal insect extract. One band was recognized with carmine extract (38-45kDa).
Cochineal carmine (E120) is used as a biologic dye in food, cosmetics and drugs. In this case, we can provide evidence of an IgE-mediated reaction.