IMMUNOREACTIVE TUMOR-NECROSIS-FACTOR-ALPHA IS ELEVATED IN MATERNAL PLASMA BUT UNDETECTED IN AMNIOTIC-FLUID IN THE 2ND TRIMESTER

OBJECTIVE: We investigated the participation of the cellular arm of th e immune system in adaptation to pregnancy by assessing plasma and amn iotic fluid levels of the cytokine tumor necrosis factor-alpha. STUDY DESIGN: Fifty-five healthy pregnant women who underwent second-trimest er genetic amniocentesis at a mean gestational age of 17.0+ +/- 1.4 we eks composed study group A. Blood was drawn from each patient before a mniocentesis, and an aliquot of amniotic fluid was obtained for this s tudy. Twenty-one healthy patients at a mean gestational age of 35.5 +/ - 4.8 weeks composed study group B, and blood was obtained from each p atient at an outpatient prenatal visit. Twenty-two healthy, nonpregnan t women of reproductive age composed the control group (C). All specim ens were stored at -70 degrees C and collectively assayed for tumor ne crosis factor-alpha by a specific enzyme-linked immunoassay. RESULTS: All patients in group A had a normal karyotype and all patients in gro ups A and B had uneventful pregnancies. Tumor necrosis factor-alpha wa s detected in the plasma of 43 of 55 (78.2%) patients in group A compa red with 7 of 21 (33.3%) patients in group B (p < 0.001); tumor necros is factor-alpha was not detected in any of the 22 women in group C. Th e median plasma tumor necrosis factor-alpha level for group A was 135 pg/ml (range 0 to 625 pg/ml) compared with 0 pg/ml (range 0 to 110 pg/ ml) in group B (p < 0.001). Tumor necrosis factor-alpha was not detect ed in any of the amniotic fluid specimens studied. CONCLUSIONS: Levels of tumor necrosis factor-alpha were elevated in the plasma but not de tected in the amniotic fluid of normal pregnant patients in the second trimester. These findings suggest involvement of the cellular branch of the immune system and its products, the cytokines, in the normal ad aptation of the mother to the fetal allograft, with a possible role in regulating trophoblast growth and invasion.