Modification of allergenic proteins with glycans for oral tolerance induction

Food allergy is defined as an unwanted response of the immune system to
harmless food proteins. For years it has been thought that the best way to
prevent the development of food allergy, is to avoid exposure to food proteins.
However, recent studies have shown that exposure is necessary to (re)train the
immune system to induce tolerance. This is an active process in which food
proteins are taken up, processed and presented by antigen presenting cells to
naïve T cells. Instead of induction of Th2 cells (allergic response), naïve
CD4+ T cells develop a regulatory or anergic phenotype (tolerogenic response).
The form in which the allergens are encountered by a subject may play a key
role for the development of oral tolerance. Previous studies have indicated
that glycans can induce immunosuppressive responses. Moreover, key cells
involved in oral tolerance development and in allergic responses express
glycan-binding proteins. In this study we would like to investigate whether
modification of allergens with glycans may support oral tolerance induction
and/or inhibit the allergic response.

This is an exploratory study with two objectives:
1. To investigate whether modification of allergenic milk and peanut proteins
or peptides thereof with glycans can support oral tolerance induction by
altering the antigen-specific T cell response from a Th2-dominant response
towards a more tolerogenic response directly or indirectly via antigen
presenting cells.
2. To investigate whether modification of allergenic milk and peanut proteins
or peptides thereof with glycans can diminish IgE-mediated responses by
inhibiting IgE production by B cells, interfering with IgE
binding/cross-linking and/or maturation of effector cells.

Cow*s milk and peanut allergic patients will be asked to donate 100 ml blood
twice. The first blood sample will be used to isolate plasma and peripheral
blood mononuclear cells (PBMCs) for the generation of cow*s milk- or
peanut-specific T cell lines/clones and autologous Epstein-Barr virus
(EBV)-transformed B cells. These cells will be used to investigate the effect
of glycans on T cell phenotype (Objective 1). Plasma will be used to study the
effect of glycans on IgE binding (Objective 2). The second blood sample will be
used for the basophil activation test (IgE cross linking), and for isolation of
allergen-specific B cells (antibody production), CD34+ progenitor cells for the
generation of mast cells (maturation effector cells) (all three Objective 2),
and monocytes for the generation of monocyte-derived DCs (MoDCs). The MoDCs
will be used as antigen-presenting cells for the T cell lines/clones (indirect
effects on T cell lines/clones) (Objective 1).

The subjects are requested to make two visits to the UMC Utrecht for a blood
withdrawal of 100 mL. The risk of blood withdrawal consists of slight pain and
possible bruising. The risk is considered negligible.