In vivo, two recently developed food allergy models in mice are being used. Mice are orally sensitized for peanut or the milk proteins whey or casein. A large range of immunological laboratory techniques are being applied in these models: Elispot, Elisa (serum antibody levels, cytokines), flowcytometry, culture of T cells and dendritic cells and immunohistology. In these in vivo models, we investigate the role of various immune cells in the initiation and maintenance of food allergy ((Van Wijk F, Nierkens S, Hassing I, Feijen M, Koppelman SJ, de Jong GA, Pieters R, Knippels LM. The effect of the food matrix on in vivo immune responses to purified peanut allergens. Toxicol Sci 2005;86(2):333-41)),((Van Wijk F, Nierkens S, de Jong W, Wehrens EJ, Boon L, van Kooten P, Knippels LM, Pieters R. The CD28/CTLA-4-B7 signaling pathway is involved in both allergic sensitization and tolerance induction to orally administered peanut proteins. J Immunol 2007;178(11):6894-900)),((Schouten B, van Esch BC, Hofman GA, van den Elsen LW, Willemsen LE, Garssen J. Acute allergic skin reactions and intestinal contractility changes in mice orally sensitized against casein or whey. Int Arch Allergy Immunol 2008;147(2):125-34)). Specific cells or cell receptors are blocked or stimulated by antibodies, and specific cells can be transferred to induce modulation of the immune response to the food allergen. In addition, potential ways to induce immunomodulation and tolerance to food allergens can be studied, including the use of prebiotics, probiotics or certain pharmaceuticals. Knowledge on these fundamental mechanisms will be translated to therapies and risk assessment approaches.