Occupational asthma to carmine in a butcher.

UNLABELLED: Hypersensitivity to carmine (E120) has been identified as a cause of food intolerance and occupational asthma. We present a case of occupational asthma following exposure to carmine in a manufacturer of sausages and review the literature.

CASE REPORT: A 42-year-old non-atopic male presented with a 5-year history of rhinoconjunctivitis and asthma on occupational exposure to food additive dusts. Symptoms increased after work. The patient had been exposed for more than 20 years.

METHODS

Skin prick tests were performed with a battery of common inhalant allergens and spices. Cochineal, carmine lake and additive mixes used by the patient were extracted and subsequently used for skin prick test, bronchial provocation and in vitro measurements (specific IgE, Western blot and chromatographic fractionation).

RESULTS

Prick tests were positive to carmine and carmine-containing additives; carmine-specific IgE and bronchial challenge tests were also positive (PC20 = 0.0004 mg/ml and 1.6 kU/l). Western blot showed IgE binding to bands of about 30 kDa on cochineal extract and a diffuse pattern at 40-97 kDa on carmine. This result was confirmed by gel filtration chromatography and dot blot. Carmine completely inhibited IgE binding to cochineal extract.

DISCUSSION: Carmine is a potential sensitizer in an occupational setting: 18 cases of occupational asthma have been described to date. Carmine allergens are poorly defined; in general, proteins from cochineal not removed by the extraction process are considered as the main allergens in carmine. Our results are consistent with this, but show that these proteins may be subject to chemical modification.