Identification of carmine allergens among three carmine allergy patients

Background: There have been several reports of carmine allergy; however, id entification of the responsible carmine allergens has not been widely docum ented. Methods: Three female patients presented with a history of anaphylaxis and/ or urticaria/angioedema after ingestion of carmine-containing foods. All th ree patients had 4 + skin prick tests to carmine. Among them, two patients were confirmed to have carmine allergy by blinded, placebo-controlled food challenges to carmine. SDS-PAGE of cochineal insects and carmine, immunoblo tting for IgE antibody with sera from all three patients, and immunoblottin g inhibition with carmine were performed. Results: SDS-PAGE of minced cochineal insects revealed several protein band s of 23-88 kDa. Several of these bands were variably recognized by our thre e patients' sera, and this reactivity was inhibited by carmine. Although no protein bands could be visualized on SDS PAGE of carmine in Coomassie bril liant blue staining, three protein bands were recognized by two of the thre e patients' serum. Conclusions: These results suggest that commercial carmine retains proteina ceous material from the source insects. These insect-derived proteins (poss ibly complexed with carminic acid) are responsible for IgE-mediated carmine allergy. Patient reactivity to these proteins may vary.