Problem
The immunophenotype of B cells at the maternal‐fetal interface (decidua) in labor at term and preterm labor is poorly understood.
Method of study
Decidual tissues were obtained from women with preterm or term labor and from non‐labor gestational age‐matched controls. Immunophenotyping of decidual B cells was performed using multicolor flow cytometry.
Results
(a) In the absence of acute or chronic chorioamnionitis, total B cells were more abundant in the decidua parietalis of women who delivered preterm than in those who delivered at term, regardless of the presence of labor; (b) decidual transitional and naïve B cells were the most abundant B‐cell subsets; (c) decidual B1 B cells were increased in women with either labor at term or preterm labor and chronic chorioamnionitis compared to those without this placental lesion; (d) decidual transitional B cells were reduced in women with preterm labor compared to those without labor; (e) naïve, class‐switched, and non–class‐switched B cells in the decidual tissues underwent mild alterations with the process of preterm labor; (f) decidual plasmablasts seemed to increase in women with either labor at term or preterm labor with chronic chorioamnionitis; and (g) decidual B cells expressed high levels of interleukin (IL)‐12, IL‐6, and/or IL‐35.
Conclusion
Total B cells are not increased with the presence of preterm or term labor; yet, specific subsets (B1 and plasmablasts) undergo alterations in women with chronic chorioamnionitis. Therefore, B cells are solely implicated in the pathological process of preterm labor in a subset of women with chronic inflammation of the placenta. These findings provide insight into the immunology of the maternal‐fetal interface in preterm and term labor.