Eosinophil activation in preterm infants with lung disease

Abstract

We investigated the role of eosinophils in the pathogenesis of bronchopulmonary dysplasia (BPD) in preterm infants. Fifteen preterm infants with BPD were compared to 13 preterms with respiratory distress syndrome (RDS) and to 16 healthy preterms. We assessed total eosinophil and neutrophil counts in venous blood samples and the levels of the eosinophilic activity markers eosinophilic cationic protein (ECP) and the cellular surface antigen (CD9). The eosinophil count was greater in BPD compared with RDS and healthy infants (1414 vs. 797 and 471 cells per microlitre, respectively, p = 0.03). ECP levels were elevated (34 vs. 12.8 and 9.8 microg/L, respectively, p = 0.002) and CD9 levels reduced (75 vs. 94 and 86 mean fluorescence intensity units, respectively, p = 0.01) in BPD compared with RDS and healthy infants, suggesting eosinophilic activation in BPD. These findings were not solely explained by differences between gestational age or birth weight of the different groups. ECP levels were positively correlated with the duration of oxygen supplementation in the BPD group. The eosinophil count fell promptly after steroid treatment was commenced in the BPD group. The findings suggest that BPD is linked to eosinophil activation, which might contribute to the pathogenesis.