A murine model of wheat versus potato allergy: Patatin and 53kDa protein are the potential allergen from potato (1)

Potato is the fourth most crucial food crop in the world with a production of 381 million tonnes in 2014 after wheat, rice and corn. Consuming potatoes for food or peeling of raw potatoes may evoke allergic reactions. Hypersensitivity to raw potato is probably owing to patatin which is the main storage protein of potato tubers, however, little information about the allergenic potentials of patatin was reported.

Preparation of potato protein was isolated from potato fruit juice. After washing and peeling, fresh potatoes were sliced and placed in a 50mM anti- browning agent sodium bi sulfite (NaHSO3) for 5–10 min and ground. The slurry was thereafter clarified at 8000 g for 1 h, the supernatant was collected and ultra-filtered, dialyzed (membrane cut-off Mw 10 kDa), lyophilized and stored at −20 °C until used.

The mice were sensitized daily by intragastric gavage with a final volume of 0.03 mL/g body weight for one week. For the stage of excite sensitization, the mice were fasted overnight and challenged with intragastric gavage with 30 mg/mL of freshly homogenized potato protein (PP) or 5 mg/mL (low dose) wheat gluten (WG) in PBS from the 2nd week up to 42 days at weekly intervals, the final volume was also 0.03 mL/g body weight.

Electrophorogram obtained by SDS-PAGE showed that the P1 included 21, 20 and 16 kDa protease inhibitors fractions, P2 was potato allergen patatin and included 43 kDa fractions, while PP showed the presence of 43, 21, 20 and 16 kDa fractions, and some other fractions.

The content of antigen-specific IgE in the mice which were sensitized by a low dose of WG (5 mg/mL) increased significantly. While in the group of mice which were sensitized with a much higher dose of PP (30mg/mL).

A significant rise in serum IL- 4 and IL- 5 levels was detected on the day 21st and reached the highest at 6th week. The level of IFN-γ in the wheat and potato sensitized group was similar, and was little higher than that of the sham group.

WG, PP, and P2 showed significantly larger diameter appearance of wheal formation. P1 was not able to be sensitized by dermal mast cells and did not give rise to significant wheal diameter in response.

All mice sensitized with wheat gluten exhibited hypersensitivity reactions, the hypersensitivity score of 14 mice was 1, two mice were 4, and other 2 mice were 5. Whereas in the PP group, four mice were asymptomatic (score was 0), and the hypersensitivity score of 13 mice was 1, only 1 mouse had the highest score. Mice sensitized with WG exhibited the most severe hypersensitivity symptoms due to that all mice had the score ≥4. Among these three proteins in potato, P2 elicited significant hypersensitivity with symptoms of systemic anaphylaxis,

Coomassie stained SDS-PAGE pattern of wheat protein showed 16 protein fractions with 7 immunogenic gluten fractions ranging from 25 to 70 kDa. Together with P1 and P2, a 53 kDa molecular mass protein was detected from the CCB-stained gel, showed IgE-binding ability by im- mune-blotting with relatively higher intensity. Another 71 kDa potato allergen was also identified through western blot. The 53 kDa band yielded primary amino acid sequencing could be identified as Adenosyl-homocysteinase of potato tuber while 71kDa allergen was an uncharacterized protein.

1. A murine model of wheat versus potato allergy: Patatin and 53kDa protein are the potential allergen from potato, (available at https://www.sciencedirect.com/science/article/abs/pii/S0161589018305522).