A03056: Validation of enzyme linked immunosorbant assay (ELISA) for the determination of latex allergens in food contact materials and associated foods

Study Duration: Leatherhead Food International

Previous work (FSA Project A03043) established that latex allergens could be detected in extracts from some food contact materials. Commercial ELISAs for four clinically relevant latex allergens: Hev b1, Hev b3, Hev b5 and Hev b6.02 were set up and a modified protocol developed which improved the detection of low levels of allergen. Recovery of allergens from adhesive spiked food samples was variable: good recovery was reported for Hev b5 and Hev b6.02 from most matrices but the recovery of Hev b3 and Hev b1 from spiked foods was low and variable. Preliminary experiments indicated that transfer of allergen to food from food contact materials was possible. In this current report, several formulations of NRL-based cold seal adhesive and five batches of bakery release film were tested for their latex allergen content. These contact materials were chosen for study in this project over transfer from latex gloves since contact with gloves would be transient and it was felt that direct food contact should be given priority.

The profile of allergens in different contact materials was investigated and various methods used to improve the recovery of allergens from foods. An inter-laboratory validation was carried out and the validated method applied to wrappers and foods collected from manufacturing sites.

The reported recoveries for Hev b5 from two food matrix categories, chocolate confectionery and frozen confectionery, were 68 ± 6% and 83 ± 3% respectively. The recoveries for Hev b6.02 were 92 ± 9% and 96 ± 8% respectively for the same two food matrix categories. An inter-laboratory comparison of the method for measuring latex allergens Hev b5 and Hev b6.02 was undertaken; good agreement in results was obtained between the two laboratories. Whilst small scale and thus fairly superficial this did serve to give some confidence that the method can give comparable results when used in a different laboratory.

The profile of allergens was different between the two types of contact material tested and there was a wide variation in the concentration of allergen between different batches of the same material. The method was successfully validated for the analysis of the latex allergens Hev b5 and Hev b6.02 from foods spiked with cold seal adhesive, however it was not possible to sufficiently improve the recovery of either Hev b1 or Hev b3 to develop a validated, quantitative method. Significant cross-reactivity was noted to gram flour (chickpea), wheat flour and rice flour, which affected the testing of food types such as biscuits and pastries, so analysis should be limited to foods which do not contain these ingredients. Hev b5 and Hev b6.02 was measured on some of the wrappers tested, but none of the foods, which were sampled from the areas most likely to be in contact with the cold seal adhesive, tested positive suggesting that the allergens had not transferred at levels above the detection limit of the method. Using the methods established in this project, it should be possible to measure latex allergen concentrations in food contact materials and Hev b5 and Hev b6.02 allergens in some types of food samples. However, the clinical relevance of the concentrations of allergen measured and the current limits of detection need to be assessed in relation to clinical data determining the amount of allergen required to cause allergic reactions in susceptible individuals.

Topping J.R., Haines J., Kneller S., Patel P., A preliminary investigation into the possible transfer of latex allergens from latex protein containing materials in contact with food, J. Sci. Food Agric., 2006, 86, 1826-1832