The immune system exhibits the capacity to react specifically towards antigens. This capacity depends on the activation of T and B cells. The cooperation between B and T cells is necessary for the production of IgG, IgA and IgE. The productions of these antibodies together with the formation of the other immune products (IgM and sensitized T cells) result in an altered state of reactivity towards the antigen. This becomes manifest in variety of ways: from protection to destruction. In the case of allergic rhinitis the tissue damage is caused by the presence of IgE and the subsequent release of vaso active amines by the mastcell after contact with the antigen.