Circulating levels and promoter polymorphisms of IL-6 and IL-8 in paediatric cancer patients with fever and neutropenia

Circulating levels of IL-6 and IL-8 were investigated as early markers for serious infections in febrile neutropenic children. Since circulating levels of IL-6 and IL-8 can be influenced by promoter polymorphisms, the study was designed to evaluate known promoter genotypes of IL-6 and IL-8 to improve the ability of the cytokines to distinguish between the different types of infection. Cytokine levels were assessed in 146 children on admission for 311 episodes of febrile neutropenia [FUO (n=209), localized infections (48), pneumonia (15), gram-negative (18) and gram-positive (21) bacteremia]. Although IL-6 levels were significantly higher in patients with bacteremia due to gram-negative organisms compared to those in patients with febrile episodes without identifiable source or with localized infections (P=.029 and P=.0045), IL-6 and IL-8 levels did not discriminate between the different groups. In addition, genotyping of the IL-6 and IL-8 promoter polymorphisms did not increase the diagnostic value of IL-6 and IL-8. The assessment of IL-6 and IL-8 levels in febrile neutropenic children is of limited diagnostic value and is not improved by genotyping for promoter polymorphisms.