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To the Editor: We read with interest the article by Schultz et al. (1), who present data on the neonatal inflammatory response.
As detection of intracellular cytokines may not necessarily correlate with extracellular cytokine concentrations, we do not totally agree with the authors' conclusions on the neonatal immune
system extracted from these data.
The authors stored blood samples for up to 24 hours at room temperature. Reinsberg et al. (2) showed that IL-8 concentrations in whole blood lysate increased significantly after 3 hours of
storage at room temperature. The authors do not show data on the influences of sample storage.
Differences in storage time between the groups may have affected the results.
Van Langevelde et al. (3) reported a maximum endotoxin concentration of 18 pg/ml in adult febrile patients. In this study a maximal LPS stimulus of 30,000 pg/ml has been used. The effect on
intracellular cytokine production may not reflect in vivo conditions.
It has been shown that labor induces cytokine production in term and preterm infants (4). Modification of cytokine synthesis by labor may differ in neonatal cells from preterm and term
infants. The diminished spontaneous production of intracellular cytokines as well as the production after ex vivo stimulation in preterm infants