[Two cases of acute eosinophilic pneumonia--analyses of cytokines in BALF before and after treatment].

Acute eosinophilic pneumonia (AEP) has been well recognized as sudden onset respiratory failure characterized by an increased eosinophilic cell count in the bronchoalveolar lavage fluid (BALF). Although several lines of research have demonstrated that the Th2 cytokine network is likely to play a pivotal role in the development of AEP, that mechanism has not been clearly understood yet. Previous reports published in Japan demonstrated that the BALF CD4/CD8 ratio in patients with AEP ranged between 1.1 and 5.8. In this report, we describe 2 cases of AEP in which the CD4/CD8 ratios were 0.3 and 7.8 when present. We measured IL-4, IL-5, IL-10 and IFN gamma in the BALF before and after treatment in these patients. IL-5 decreased drastically after the treatment phase, while the other cytokines did not change much. We concluded that the IL-5 concentration in the BALF is probably related to the development of AEP. In addition, we also speculated that the CD4/CD8 ratio in BALF from patients with AEP may be affected whether a patient has an atopic background or not.