Association between fever and serum interleukin-6 levels in children with group a β-hemolytic streptococcal infection

1. 1|The serum levels of interleukin (IL)-1β, IL-6 and granulocyte colony-stimulating factor (G-CSF) were measured in children with Group A β-hemolytic streptococcal (GABHS) infection using sensitive immunoassays. 2. 2|Serum IL-6 levels were elevated in 21 27 patients during the phase of GABHS antigen-detection, significantly higher than in healthy control children (P < 0.01). Levels of IL-1 were undetectable in all but one sample. 3. 3|The IL-6 level peaked on day 3 of the infection, then decreased. The IL-6 levels were significantly associated with the duration of fever (P < 0.05) and the maximum body temperature (BT) (P < 0.05), but not with the BT at time of blood sampling, C-reactive protein levels or leukocyte counts. 4. 4|Levels of G-CSF were slightly higher in the patients with infection than in the controls (P < 0.05), but were not correlated with any other parameter including neutrophil counts. 5. 5|These cytokine levels neither reflected a differing T-serotype infection, nor did they vary among patients with regard to the presence of skin eruptions and the carrier state. 6. 6|These observations suggest that IL-6, but not IL-1, is produced during the acute phase of GABHS infection, accounting for the febrile condition as an inflammatory cytokine, despite the serotype of the infecting organism or the clinical types of infection.