SOLUBLE TUMOR-NECROSIS-FACTOR RECEPTORS IN MATERNAL PLASMA AND 2ND-TRIMESTER AMNIOTIC-FLUID

OBJECTIVES: We assessed maternal plasma and second-trimester amniotic fluid for levels of the p55 and p75 soluble tumor necrosis factor rece ptors. STUDY DESIGN: Blood was drawn from 61 healthy pregnant women (g roup A) before second-trimester genetic amniocentesis, and an aliquot of amniotic fluid was also obtained for this study. An additional bloo d sample was obtained from 13 of these patients at 36 to 40 weeks' ges tation. Twenty-three healthy, nonpregnant women of reproductive age do nated blood as a control group (group B). All plasma and amniotic flui d specimens were collectively assayed for the p55 and p75 soluble tumo r necrosis factor receptors by specific enzyme-linked immunoassays. Ad ditionally, tumor necrosis factor-alpha concentrations were measured i n second-trimester plasma and amniotic fluid of 22 patients in group A and in all 23 of the nonpregnant women. RESULTS: The p55 and p75 solu ble tumor necrosis factor receptors were detectable in all plasma samp les from both groups of patients. The concentrations of both soluble r eceptors were significantly higher in second-trimester plasma compared with nonpregnant measurements (p < 0.01), and the plasma concentratio ns of both soluble receptors increased significantly from the second t o third trimester (p < 0.01). The p55 and p75 soluble tumor necrosis f actor receptors were also detectable in all amniotic fluid samples. Tu mor necrosis factor-alpha was detected in the plasma of 15 of 22 patie nts in the second trimester but in none of the amniotic fluid samples and in none of the plasma samples from the nonpregnant cohort. CONCLUS IONS: Both the p55 and p75 soluble tumor necrosis factor receptors are physiologic constituents of second-trimester maternal plasma and amni otic fluid. Concentrations are elevated in pregnancy and further incre ase from the second to third trimester.