The Effect of the Food Matrix on In Vivo Immune Responses to Purified Peanut Allergens (1)

Major food allergens, in general, are glycoproteins ranging from 10 to 70 kDa that are abundant in the food and that possess multiple IgE binding epitopes.

After injection with PE fat or PE, total lymph node cell numbers increased significantly (fourfold), and no difference was found between the PE fat- and PE-treated groups. In contrast, no cell proliferation was ob- served after injection with the purified peanut allergens Ara h 1, Ara h 2, or Ara h 6.

Popliteal lymph node cells derived from PE- and PE fat-treated mice secreted similar high amounts of IL-4, IL-10, and IFN-c compared to cells derived from control mice. No Th2 or Th1 bias was observed in either of the PE treatment groups. With respect to the purified allergens, no significant IL-10 or IFN-c cytokine production was found in PLN cell cultures of Ara h 1-, Ara h 2-, and Ara h 6-treated groups, and only Ara h 6-injection resulted in significant IL-4 production upon restimulation with Con A.

Popliteal lymph node LN cell cultures derived from PE- and PE fat-treated mice restimulated with PE induced high levels of IL-2, IL-4, IL-10, and IFN-g.

Both PE fat and PE injection significantly augmented the percentages of CD80-, CD86-, and CD54-expressing cells in the PLN, whereas no increase was found after injection with Ara h 1, Ara h 2, or Ara h 6.

Mice were dosed by gavage for 4 weeks with PE (1 and 6mg), Arah1,Arah2,Arah3,orArah6(0.1and1mg)inthe presence of the mucosal adjuvant CT. All purified allergens were able to induce specific IgE responses, but only for Ara h 1 treatment was a significant difference found between the 0.1 and 1 mg dosing group.

In the absence of CT, only low levels of IgG1 and IgG2a, and no IgE, were found, with no differences between the PE fat- and PE-treated group. In the presence of CT, similar high levels of IgG2a, IgG1, and IgE were found in both PE treatment groups.

Mice therefore need an accompanying adjuvant (in the case of PE provided by the food matrix) to be able to activate APC and to induce subsequent immune stimulation. Peanut oils can have an adjuvant effect in a vaccine model. In addition to nutrients, non-nutritive compounds such as lectins and food contaminants such as LPS and aflatoxins may affect immune responses to food proteins.

in vitro, polysaccharide–protein and protein–protein interactions may influence allergen digestion, these interactions seemed not to affect the immune response to allergens in the present in vivo model.

1. Van Wijk, Nierkens, Hassing, Feijen, The Effect of the Food Matrix on In Vivo Immune Responses to Purified Peanut Allergens. Toxicol. Environ. Chem. (2005) (available at https://academic.oup.com/toxsci/article-abstract/86/2/333/1653582).