Objective:
To determine the cytokine response to lipopolysaccharide in patients in the intensive care unit.
Patients:
Patients in a mixed medical/surgical intensive care unit with fever and a de novo clinical dysfunction of at least one organ system.
Methods:
Whole blood from patients and from laboratory controls was stimulated with 8 ng/mL of lipopolysaccharide (Escherichia coli 0111:B4) at 37°C, and tumor necrosis factor α (TNF-α) was measured using enzyme linked immunosorbent assay at 4,8, and 24 hours. The same subjects' purified monocytes were cultured with 8 ng/mL of lipopolysaccharide in the presence of autologous or pooled control plasma or cocultured with purified autologous polymorphonuclear leukocytes at a polymorphonuclear leukocyte—monocyte ratio of 10:1, and TNF-α was measured at 24 hours using the enzyme linked immunosorbent assay.
Results:
We detected high (n=5) and low (n=5) TNF-α responders in whole blood producing a mean (±SEM) of 27.2± 6.3 pg/mL per 1000 monocytes vs 0.0±2.4 pg/mL per 1000 monocytes, respectively (controls, 58.0±13.0 pg/mL per 1000 monocytes). The kinetics of TNF-α production in both groups were comparable. Purified monocytes from both groups of patients cultured with lipopolysaccharide alone produced equivalent TNF-α values (42.4±10.5 vs 40.8± 12.5 pg/mL per 1000 monocytes). Assayable TNF-α was not different with autologous vs control serum but was markedly diminished by the presence of polymorphonuclear leukocytes in patients as well as in controls; the two groups of patients did not differ in this polymorphonuclear leukocyte effect.
Conclusion:
Lipopolysaccharide stimulation of monocytes in the whole blood results in marked variation of TNF-α production. This phenomenon may account for the variable septic response to infection in patients in the intensive care unit.(Arch Surg. 1994;129:187-192)