[Hypereosinophilic reactions in hypersensitivity states]

Among eosinophil-related diseases, many of them are linked to hypersensitivity mechanisms which are dependent or independent on the development of an IgE response. In certain patients a clear relationship can be identified with an environmental airborne allergen: allergic disorders associated with the presence of eosinophils present in blood or in the airway lumen include allergic asthma, perennial or seasonal allergic rhinitis, less often allergic sinusitis or some cases of chronic cough. In other clinical situations, proofs for a direct involvement of IgE are difficult to establish, for example in drug-induced pulmonary eosinophilias. In allergic bronchopulmonary aspergillosis, two distinct mechanisms are implicated: an IgE dependent process but also the proliferation of the fungal microorganism into the bronchial tree. Similarly in Churg++ and Strauss syndrome, it does not exist any demonstration for an IgE mechanism, although a large majority of patients are atopic, with high serum total IgE levels. So it appears that the border between IgE and non IgE related disorders remains at the present time poorly defined.