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 μg/mL). After incubation for 4 hours (37°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-α, interleukin-1β, 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-α (mean 50.20 ± 5.80 vs 31.29 ± 5.57, P> .05). No significant difference was seen in the production of interleukin-1β (mean 58.22 ± 11.09 vs 47.18 ± 7.88, P> .05). Conclusion: The percentage of interleukin-12 and tumor necrosis factor-α producing monocytes is decreased in pregnant women compared with nonpregnant women, suggesting that pregnancy is a proinflammatory state. (Am J Obstet Gynecol 2003;188:1073-7.)