Fig. 2. Schematic of tissue and blood eosinophilia in acute eosinophilic pneumonia (AEP).

(A) At the onset of AEP, there is a rapid recruitment of blood eosinophils into the lung, resulting in a normal-range blood eosinophil count. (B) After treatment with systemic steroids, the eosinophilic lung inflammation is resolved, mainly through the induction of eosinophil apoptosis in the lungs. The decreased recruitment of blood eosinophils into the lung might result in the retention of eosinophils in circulation, leading to a transient blood eosinophilia.