Tumor necrosis factor-α in whole blood cultures of preeclamptic patients and healthy pregnant and nonpregnant women

Objectives: Tumor necrosis factor-α (TNF-α) is recognized as a likely mediator of the excessive endothelial activation and injury that is a key pathogenetic mechanism of preeclampsia. We used whole blood cell cultures from 12 patients with severe preeclampsia and from 12 healthy pregnant and nonpregnant women to determine the release of TNF-α by unstimulated leukocytes as a measure of their state of activation, and their response to stimulation with lipopolysaccharide (LPS) as an indicator of their state of priming. Methods: Blood was cultivated without and with LPS, and TNF-α release was measured after six and 24 hours of cultivation by enzyme-linked immunoassays. Differential leukocyte counts were performed, and TNF-α values calculated per 105 monocytes. Results: In unstimulated whole blood cultures, TNF-α release after six hours of cultivation was similar in all three groups; but after 24 hours, TNF-α concentrations in culture supernatants from preeclamptic patients were significantly higher than were values obtained in blood from normotensive pregnant women. In LPS-stimulated blood cultures with a maximum of TNF-α release at six hours cultivation time, TNF-α concentrations were significantly lower in preeclamptic women than they were in both control groups. We showed in an additional experiment that a strong LPS challenge following preactivation with high doses of LPS resulted in reduced release of TNF-α compared with release of TNF-α following preactivation with low doses of LPS. Conclusions: The observed high capacity for spontaneous TNF-α release by leukocytes in preeclampsia indicates activation of TNF-α producing leukocytes by the disease process. Preactivation and exhaustion of leukocytes by leakage of TNF-α could lead to the reduced response to TNF-α inducer LPS as observed in blood cultures from preeclamptic patients.

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