Problem: This study was designed to examine immunological changes in maternal peripheral blood and the relationship of these changes with the amount of fetal cells in the blood.
Method of study: The expression of interleukin-4 (IL-4), IL-8, IL-18 and fetal hemoglobin gamma chain (HbF-γ chain) messenger RNAs (mRNAs) in maternal peripheral blood was measured by a quantitative reverse transcription-polymerase chain reaction method.
Results: In maternal peripheral blood, the expression of IL-4 mRNA was up-regulated from the second gestational month (GM) to delivery. The expression of IL-8 and IL-18 mRNAs was down-regulated from the third or fourth GM until the eighth or ninth GM, respectively, and both increased before the onset of labor, though IL-4 mRNA decreased. The expression of IL-8 and IL-18, but not IL-4, mRNAs was correlated with that of HbF-γ chain mRNA.
Conclusions: Immunological interactions between maternal peripheral immune cells and fetal cells appear to be related to the onset of labor.