An elevated fetal interleukin-6 concentration can be observed in fetuses with anemia due to Rh alloimmunization: implications for the understanding of the fetal inflammatory response syndrome

Methods. aEuro integral Fetal blood sampling was performed in sensitized Rh-D negative women with suspected fetal anemia (n aEuroS== aEuroS16). Fetal anemia was diagnosed according to reference range nomograms established for the assessment of fetal hematologic parameters. An elevated fetal plasma IL-6 concentration was defined using a cutoff of > 11 pg/ml. Concentrations of IL-6 were determined by immunoassay. Non-parametric statistics were used for analysis. Results. aEuro integral(1) The prevalence of an elevated fetal plasma IL-6 was 25%% (4/16); (2) there was an inverse relationship between the fetal hematocrit and IL-6 concentration -- the lower the hematocrit, the higher the fetal IL-6 (r aEuroS== aEuroS--0.68, p aEuroS== aEuroS0.004); (3) fetuses with anemia had a significantly higher plasma IL-6 concentration than those without anemia (3.74 pg/ml, interquartile range (IQR) 1.18--2.63 vs. 1.46 pg/ml, IQR 1.76--14.7; p aEuroS== aEuroS0.02); (4) interestingly, all fetuses with an elevated plasma IL-6 concentration had anemia (prevalence 40%%, 4/10), while in the group without anemia, none had an elevated fetal plasma IL-6. Conclusions. aEuro integral An elevation in fetal plasma IL-6 can be observed in a subset of fetuses with anemia due to Rh alloimmunization. This observation suggests that the hallmark of FIRS can be caused by non-infection-related insults. Further studies are required to determine whether the prognosis of FIRS caused by intra-amniotic infection/inflammation is different from that induced by alloimmunization.