Endotoxin-induced cytokine production of monocytes of third-trimester pregnant women compared with women in the follicular phase of the menstrual cycle

OBJECTIVE: Little is known about the function of the innate immune response during pregnancy. We therefore investigated monocyte cytokine production, as a measure of monocyte function, in pregnant women compared with nonpregnant women. STUDY DESIGN: Whole blood of women in the follicular phase (day 5-6) and of healthy pregnant women (30 weeks) was collected and stimulated with endotoxin (2 microg/mL). After incubation for 4 hours (37 degrees C, 5% carbon dioxide), red blood cells were lysed and white blood cells were permeabilized, followed by staining with anti-CD14 (fluorescein isothiocyanate labeled) and with phycoerythrin-labeled tumor necrosis factor-alpha, interleukin-1beta, or interleukin-12. The cells were analyzed by flow cytometry after fixation. Results are expressed as a percentage cytokine producing cells after endotoxin stimulation. Statistical analysis was performed with the Mann-Whitney U test (P <.05). RESULTS: Compared with the percentage endotoxin-induced cytokine producing peripheral monocytes in women in the follicular phase, this percentage in pregnancy was decreased for interleukin-12 (mean 6.63 +/- 1.34 vs 3.34 +/- 0.87, P <.05) and tumor necrosis factor-alpha (mean 50.20 +/- 5.80 vs 31.29 +/- 5.57, P >.05). No significant difference was seen in the production of interleukin-1beta (mean 58.22 +/- 11.09 vs 47.18 +/- 7.88, P >.05). CONCLUSION: The percentage of interleukin-12 and tumor necrosis factor-alpha producing monocytes is decreased in pregnant women compared with nonpregnant women, suggesting that pregnancy is a proinflammatory state.