Pregnancy, cytokines, and disease activity in systemic lupus erythematosus.

OBJECTIVE: To evaluate levels of selected cytokines and soluble receptors involved in the humoral immune response during pregnancy in systemic lupus erythematosus (SLE) patients. METHODS: Seventeen consecutive SLE patients and 8 matched healthy controls were prospectively studied during pregnancy. Sera were obtained within the last 3 months prior to pregnancy; at 9, 17, and 29 weeks of pregnancy; and at 1 month after delivery. Serum levels of interleukin-10 (IL-10), interleukin-6 (IL-6), and soluble tumor necrosis factor receptors p55 (sTNFR I) and p75 (sTNFR II) were evaluated. SLE activity was measured by the European Consensus Lupus Activity Measurement score modified for pregnancy. RESULTS: IL-10 serum levels were found to be higher (P <0.0001) in patients than in controls before conception, and still higher (P <0.0001) in SLE patients during gestation, without intertrimester changes. In SLE patients, IL-6 serum levels did not increase in the third trimester of pregnancy, as was observed in controls (P=0.011). No significant differences between SLE patients and controls were found in either sTNFR I or II levels or profiles before and during pregnancy. IL-10 and sTNFR I levels were significantly higher during pregnancy and postpartum in SLE patients with active disease (P=0.03 and P=0.01, respectively). CONCLUSION: The levels of some cytokines involved in the humoral immune response seem to be modified in the peripheral circulation of pregnant SLE patients. The most relevant modifications are the lower than expected increase of IL-6 in the third trimester of gestation and persistently high levels of IL-10 during pregnancy.