Background: Eosinophilia is a common finding in neonatal units. The role of eosinophilia in preterm infants is uncertain. The aim of the study was the assessment of absolute eosinophil count (AEC) and eosinophil cationic protein (ECP) concentration in the blood of VLBW infants during the first 4 weeks of life.Material/Methods: Prospective study in the University Hospital NICU included 58 preterm infants with gestational age 24–34 weeks (x±SEM: 28.8±0.3) and mean birth weight 127±31 g. AEC, ECP ant total IgE levels at admission, and at the age of 10, 20 and 30 days of life were measured.Results: There were no correlations between AEC and gestational age (R=0.14, p=0.33) or birth weight (R=0.13, p=0.34), and between ECP and gestational age (R=-0.05, p=0.8) or birth weight (R=0.11; p=0.53) either. There were significant correlations between AEC and ECP at admission (R=0.46; p=0.001) and after the 5th day of life (R=0.51; p 1500/mm3 was observed in 26 (44%) children. Significant eosinophilia was recognized on average on the 24th day of life. Only 3 children had positive total IgE levels (>2kU/l). There were no correlations between AEC or ECP and total IgE levels.Conclusions: There is a correlation between AEC and ECP confirming that an increased number of eosinophils in preterm infants is connected with increased activity of eosinophils.

Keywords: VLBW infants, ECP, Immunoglobulin E, Eosinophilia, Eosinophil Cationic Protein, IgE