Soluble tumour necrosis factor receptors,tumour necrosis factor and interleukin-6 in serum in granulocytopenic patients with fever

Serum levels of TNF, IL-6 and soluble TNF receptors p55 and p75 (sTNFR-p55 and sTNFR-p75) were examined in 14 patients with acute myeloid leukaemia during 43 courses of chemotherapy. The patients experienced 30 episodes of fever which occurred during granulocytopenia (defined as granulocyte counts <0.2×10⁹/1) and six fever episodes when granulocyte counts were >1.0×10⁹/1. Febrile episodes were classified as microbiologically defined infection, clinically defined infection, and unexplained fever. Levels of bioactive IL-6 and immunoreactive TNF increased in response to fever during granulocytopenia, whereas bioactive TNF was not detected in any sample in this study. During granulocytopenia, both sTNFR rose significantly in microbiologically defined infection (P<0.01 for sTNFR-p55 and P<0.05 for sTNFR-p75), but not in the other two categories. The ratio of sTNFR-p55 to sTNFR-p75 was higher during febrile periods in granulocytopenia than in a non-granulocytopenic situation with granulocyte counts >1.0×10⁹/1 (P<0.01). We conclude that granulocytopenia affects release of the two sTNFR differently during febrile periods, and that release of sTNFR-p75 in response to fever is reduced during granulocytopenia, suggesting a role for the granulocytes in systemic release of sTNFR-p75.