Differential diagnosis of Th1/Th2-response by T-cell and monocyte function between sepsis and non-infectious SIRS via flowcytometry

Objective

Under systemic inflammatory response syndrome (SIRS), a change in Th1/Th2-response by T-cell and a defect in monocyte function is observed, which may lead a derangement of immunological homeostasis, associated with immunosuppression and susceptibility to sepsis. We have recently developed an immune-inflammatory monitoring system, that can detect a constitutional change in Th1/Th2-population of T-cell subsets and monokine production by monocyte, via multi-parameter flowcytometry. The aim of this study was to investigate whether these tests were useful in establishing the difference between septic SIRS and non-septic SIRS.

Patients and methods

In the septic SIRS group, 11 patients with sepsis followed by organ dysfunction were studied on admission to ICU in our hospital. In the non-septic SIRS group, 10 patients who underwent major elective surgery were studied on the first and third day after operation. We investigated the cytokine expression of T-cells after activation by ionomycin and PMA, and the expression of monokine and HLA-DR antigen by monocytes after being stimulated with LPS and/or IFN-gamma, using whole blood culture (6 hours). After stain for cell-surface phenotypes, the cells were fixed and permeabilized, then fluoro-immunostained for intracellular IFN-gamma, IL-4 in T-cells, and TNF, IL-6, and IL-12 in monocytes. The frequencies of these cytokines-producing cells were estimated with multicolor flowctyemetric analysis.

Results

1) The number of IL-4 producing cells (Th2) in T-cells increased significantly both in CD4+ and CD8+ subsets in patients with sepsis, but not in patients with non-septic SIRS. While the IFN-gamma producing cells (Th1) increased slightly in patients with sepsis and non-septic SIRS. 2) The production of IL-6, TNF, IL-12 by monocytes from patients with sepsis and non-septic SIRS was significantly decreased, together with a reduction of HLA-DR expression. Afterwards, the defect of TNF and IL-12 production in monocytes from non-septic SIRS patients recovered by the third postoperative day.

Conclusion

These findings show a significant shift of Th2 response in T-cell subsets and a prolonged reduction of TNF and IL-12 production with a reduced HLA-DR expression by monocyte in sepsis, compared with those in non-septic SIRS. These tests may be available for the differentiation of immunosuppression subsequent to sepsis from the SIRS with a dominant pro-inflammatory state.

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