Abstract: The present invention is related to a method for modulating the immune system of a mammal patient towards an allergen, which comprises the step of inducing a pre-sensitisation of the immune system of said patient towards an immunogen carrying at least one T cell epitope homologous and functionally similar to an epitope present on said allergen and deriving from a naturally-occurring antigen in order to modify the response of said patient to a further sensitisation to said allergen, allowing that the immune response towards the allergen is modulated and that no allergy towards said allergen will be developed in said patient.