Natalizumab (Tysabri?) is usually a leukocytes chemotaxis inhibitor that decreases the leukocytes passage through the hematoencephalic barrier and it is currently used in relapsing-remitting forms of multiple sclerosis (MS). tomography scan exhibited pulmonary infiltrates. The bronchoscopy with the bronchoalveolar lavage resulted in eosinophilic alveolitis. No evidence of bacterial fungal and parasitic contamination connective tissue disease or vasculitis were observed. After discontinuation of natalizumab the patient improved without other treatments. As MS BIBW2992 is usually a prevalent disease and the use of natalizumab is increasing we consider important to explain that this drug can be associated with pulmonary eosinophilia especially in patients with allergic rhinoconjunctivitis or asthma. as a child. Remittent-recurrent MS was detected in 1996 and treatment with interferon was initiated changing to natalizumab in 2013 due to persistent activity of the disease. In November 2014 she began to experience watery rhinorrhea wheezing in the chest coughing and spitting up sputum. She consulted with her major physician who began BIBW2992 treatment with amoxicillin/clavulanic acidity inhaled glucocorticoids bronchodilator agencies and antihistamines leading to moderate improvement. 90 days afterwards she consulted once again with dyspnea at rest and persistent coughing the prior 48 h. The physical evaluation revealed air saturation of 91% when inhaling and exhaling ambient atmosphere with bilateral wheezing and she was used in our tertiary referral Tmem1 medical center. Both best times the administration occurred in the last 24 h. A bloodstream test BIBW2992 on appearance to the er demonstrated leukocytosis 17 200 cells/mm3(13 670 cells/mm3 neutrophils 490 cells/mm3 eosinophils) and arterial bloodstream gas check (breathing air at 0.24) showed: pH 7.47 PCO234 mmHg PO266 mmHg and HCO325 mmol/L. The upper body X-ray demonstrated reticular opacities with basal predominance and the right perihilar condensation. Urine antigens for and pneumoniae had been negative. Treatment with short-acting piperacillin-tazobactam and bronchodilators was started and BIBW2992 she was admitted towards the Pneumology Section. During her medical center stay a thoracic computed tomography (CT) check was completed [Body 1a] which demonstrated “interstitial lung disease seen as a bilateral diffuse ground-glass attenuation in colaboration with intralobular lines (crazy BIBW2992 paving design) plus some bronchiectasis.” Body 1 (a) Axial portion of thorax computed tomography check at lung home window showing regions of bilateral ground-glass attenuation. (b) Axial portion of thorax computed tomography check at lung home window showing resolution from the ground-glass areas The control bloodstream test showed continual leukocytosis (17 0 cells/mm3) and eosinophilia (1 400 cells/mm3). Exams for autoimmune disease connective tissues disease and vasculitis had been harmful; these included antinuclear antibodies anticytoplasm of neutrophils anti-DNA anti-Sm anti-ribonucleoprotein anti-Ro anti-La anti-centromere anti-SCL 70 anti-Jo 1 anti-citrullinated peptide and rheumatoid factor. Immunoglobulins BIBW2992 were also analyzed; all results were normal except IgE (total value of 153 kU/L). Precipitins (Aspergillus fumigatus excrement and serum of pigeon and parakeet) were also unfavorable. Serial coprocultures ruled out parasites. The bronchoscopy did not show endobronchial lesions and the bronchoalveolar lavage resulted in eosinophilic alveolitis (83% macrophages 4 lymphocytes 1 neutrophils and 12% eosinophils). Cultures for bacteria mycobacteria fungi and studies for parasites and computer virus were unfavorable. Lung function test detected a moderate airflow obstruction with a positive bronchodilator test and severe reduction of the carbonic monoxid (CO)-transference FEV1/FVC 82% FEV153% ref. FVC 52% ref. TLC 85% ref. RV/TLC 60% DLCO 48% ref. KCO 66%.ref. The producing diagnosis was “pulmonary eosinophilia associated with natalizumab treatment in a patient with bronchial asthma” and the Neurology Department was asked for an alternative treatment. As the patient improved with inhaled corticosteroids and bronchodilators (without systemic corticosteroids) she was discharged a week later with the same treatment. At the monitoring visit a.