Circulating interleukin (IL)-1 beta, IL-6 and tumor necrosis factor-alpha in children with febrile infection--a comparison with C-reactive protein.

Circulating interleukin (IL)-1 beta, IL-6, and tumor necrosis factor (TNF)-alpha were examined in 42 febrile children with fever lasting more than 4 days. Their diagnosis were probable viral syndrome in 22, urinary tract infection (UTI) in 10, and probable bacterial pneumonia in 10. None of our study patients had detectable serum IL-1 beta. TNF-alpha levels were significantly higher in children with pneumonia than in those with viral syndrome (p < 0.01). Children with UTI and pneumonia had significantly higher IL-6 and CRP, compared to those with probable viral syndrome (p < 0.01 for both IL-6 and CRP). When appropriate cutoff values are chosen, IL-6 had greatly improved specificity (86.4%, > 20 pg/ml) to demonstrate UTI and pneumonia, as compared to that using CRP (48%, > 40 mg/l). After three days' antibiotic treatment, IL-6 fell to control levels in children with UTI and pneumonia, while CRP remained elevated. There was no difference in TNF-alpha values before and after treatment. Thus, IL-6, rather than IL-1 beta and TNF-alpha, may be a helpful diagnostic tool for evaluation of pediatric febrile infection. Sequential studies involving more patients are needed to determine whether IL-6 is better than CRP in this clinical setting.