Altered B cell subset distribution and expression of PD-1 in preeclampsia patients.

[BACKGROUND AND AIM] The role of the programmed cell death protein-1/programmed death ligand-1 (PD-1/PD-L1) axis in the pathogenesis of preeclampsia (PE) is currently a subject of research interest. This work aimed to characterize different B cell subsets and their PD-1 expression levels in 54 PE patients compared with 21 age-matched women having normal, uncomplicated pregnancies of comparable gestational age. Also, to evaluate the possibility of a relation between the levels of these subsets with disease severity and the antihypertensive therapy.

[METHODS] B cell subsets were characterized based on the relative expression of CD24 and CD38, and their expression of PD-1 was evaluated in all participants by flow cytometry.

[RESULTS] The percentage of naïve B cells decreased significantly, while the percentage of plasmablasts increased significantly in PE patients compared with women having normal pregnancies. PD-1 expression by naïve, transitional, and memory B cells increased substantially in PE patients than in women with normal pregnancies. Naïve B cells had inverse relations with total protein level and positive correlations with systolic and diastolic blood pressure only in the PE patients not receiving antihypertensive therapy.

[CONCLUSION] PE is most probably accompanied by increased B cell activation. The results of the current study point to the critical role played by B cells and PD-1 expressing B cell subsets in PE pathogenesis, progression, and severity. However, the precise impact of PD-1 on B cell activity in pregnant women developing PE necessitates further study.