Differential leukocyte count in babies treated with natural surfactant.

The potential of exogenous replacement therapy in surfactant-deficient states such as neonatal respiratory distress syndrome (RDS) is an area of intense clinical interest today. At present, a fundamental problem with any type of exogenous surfactant is the uncertainty about potential effects on physiological defense mechanisms, such as differentiation and mobilization of peripheral leukocytes. Considering that newborn infants with proven bacterial infections have abnormal values of segmented (neutrophil) and nonsegmented (band) polymorphonuclear leukocytes, we studied 42 placebo- versus Curosurf-treated babies with severe RDS. Differential white blood cell (WBC) count was serially performed before and after treatment during the first days of life. The statistically significant increase in the proportion of bands in surfactant-treated babies did not coincide with clinical and bacteriologic evidence of possible infection. Some molecular interaction mechanisms influencing immature to mature WBC ratio are supposed. Among a variety of influences on the leukocyte count, surfactant replacement therapy needs to be considered for proper interpretation of hematologic data in babies treated for RDS.