We cannot exclude that there were subjects with ongoing infection in our preterm group at very subclinical stage as concentrations of both CRP and IL-6 were not significantly changed in examined groups, nor can we reject the hypothesis of diminished receptor binding potential since complement component 5a receptor 1 gene (C5AR1) expression was significantly downregulated in our preterm neonates group (fold=-4.32), when compared to term neonates. The gene discussed is IL6; the disease is infection.