Eosinophilic alveolitis in immunologic interstitial lung disorders.

To analyze the role of eosinophils in alveolitis due to immunological interstitial lung disorders, 568 bronchoalveolar lavage (BAL) from 537 patients affected by 13 types of interstitial lung disease involving immunologic mechanisms were considered. An arbitrary cut-off of 4% of eosinophils in BAL was assumed. In five (idiopathic pulmonary fibrosis (IPF), allergic bronchopulmonary aspergillosis (ABPA), amiodarone-induced pneumonitis (AIP), chronic eosinophilic pneumonia (CEP), Churg-Strauss syndrome (CSS)) out of the thirteen groups we took into consideration, the level of eosinophils was greater than 4%. In CEP and CSS in particular, the arbitrary cut-off of 4% was greatly exceeded (28.9% +/- 27.4, p less than 0.01 and 33.6% +/- 14.5, p less than 0.01, respectively). In the same two groups the increase of eosinophils in BAL was isolated with a direct correlation to the number of eosinophils in blood. By contrast, the increase of eosinophils in BAL of IPF, AIP and ABPA was of lesser extent (4.7% +/- 5.7 p less than 0.01, 5.0% +/- 3.0 p less than 0.01 and 6.1% +/- 10.4 p less than 0.01, respectively) and was accompanied by an increase of neutrophils in IPF, of lymphocytes in AIP and both in ABPA. These patterns are generally defined as "mixed alveolitis." On the basis of these data we conclude that the term "eosinophilic alveolitis" should be reserved for CEP and CSS.