Increase in interleukin-6 serum level preceding fever in granulocytopenia and correlation with death from sepsis.

Serum interleukin (IL)-6 levels measured by ELISA were correlated with the clinical course of 53 adults with hematologic malignancies in 95 episodes of chemotherapy-induced leukocytopenia (< 1000/microL). The median IL-6 level was 15 pg/mL (range, < 3-123) in 27 episodes without fever. This level was 14.5 pg/mL (range, < 3-187) 72-48 h before onset of fever, 78 pg/mL (range, < 3-170) 24 h before fever in episodes with unexplained fever (FUO), and 182 pg/mL (range, 63-1076) 24 h before fever in episodes with positive blood cultures (P < .001). Within 24 h after onset of fever, median IL-6 level was 171 pg/mL (range, 53-1134) in episodes of FUO, 444 pg/mL (range, 38-7973) in episodes with gram-negative bacteremia, and 2017 pg/mL (range, 76-7253) with gram-positive bacteremia (P < .01). IL-6 levels increased before death in all 13 patients who died of sepsis. Median level was 7253 pg/mL (range, 445-95,906) within 3 days of death. Determination of IL-6 may be useful for early assessment and as a prognostic tool in leukocytopenic fever.