Summary. Serum concentrations of tumour necrosis factor alpha (TNF-α), interleukin-1 receptor antagonist (IL-1ra), interferon gamma (IFN-γ), interleukin-6 (IL-6) and interleukin-10 (IL-10) were studied in 31 patients with haematological malignancies during febrile neutropenia. Samples were obtained when blood cultures were performed (time 0) and, when possible, after 2, 4, 6, 12 and 24 h. Increased levels of all cytokines were detected after start of fever with peak values in gram-negative (Gr−) bacteraemias after 2 h (TNF-α, IL-lra and IFN-γ), 4h (IL-6) and 6 h (IL-10), respectively. At time 0 the median TNF-α value was higher in the Gr− group (80 pg/ml; range 54-516 pg/ml) as compared to both gram-positive bacteraemias (Gr+, 14pg/ ml; range 7-60 pg/ml; P < 0 05) and blood culture negative episodes (BCN, 8pg/ml; range 0-87pg/ml; P<0 05).
Furthermore, the peak values of TNF-α, IL-lra, IL-6 and IL-10 during the 24 h study period were significantly and/or numerically higher in the Gr- group in comparison to the Gr+ and BCN groups, respectively. It may be concluded that neutropenic patients have increased levels of both pro- and anti-inflammatory cytokines at start of fever, with the highest values recorded during the first hours in Gr- bacteraemias. Prospective studies will show whether monitoring of serum cytokines may be used as an early diagnostic tool before results of blood cultures are available, which may have important therapeutic implications.