Immune properties of cry1Ab transgenic maize studied in mouse models of airway and food allergy

Abstract

The genetically modified maize event MON810 has been inserted with a processed version of the transgene, cry1ab, derived from the soil bacterium Bacillus thuringiensis (Bt) to express proteins with insecticidal properties. The introduced toxin may confer risks of immunogenicity, allergenicity and/or adjuvanticity to humans as well as domestic and wild animals, via inhalation of pollen and plant debris, or trough consumption of MON810 containing food and feed. The lack of knowledge regarding immune effects after airway exposure and the possible adjuvant capacity encouraged us to investigate the immune properties of Cry1Ab proteins in two mouse models of allergy. Mice were intranasally or intragastrically exposed to Cry1Ab protein as purified protein preparations or as MON810 plant material. Humoral and cellular immune parameters were determined in sera, lung lavages and in cells cultures from harvested lymph nodes and spleens. Within the limits of our study design and dose range of Cry1Ab proteins, our data gave no indication of an adjuvant capacity of Cry1Ab, irrespective of Cry1Ab protein version and exposure route. The clear humoral response induced after airway exposure to purified Cry1Ab protein preparations, without an added adjuvant, however, suggested that these proteins may have both immunogenic and allergenic properties. The results confirm that airway exposure to Cry1Ab proteins may be a relevant route of exposure. Our data do not indicate that intragastric exposure to Cry1Ab induces immunogenic or allergenic responses in mice. Furthermore, at the present doses we did not find any indication of immunogenic, allergenic or adjuvant properties of MON810 plant material irrespective of exposure route. Well-designed experiments with purified plant proteins, relevant doses and exposure routes as well as long term exposure, need be conducted to further evaluate exposures experienced in real life situations.