Low expression of human leukocyte antigen-g (HLA-G), low expression of killer immunoglobulin-like receptor (KIR), and high expression of human leukocyte antigen-c (HLA-C) in the placenta as risk factors for preeclampsia

Background: The pathogenesis of preeclampsia involves immunological factors, such as Human Leukocyte Antigen-G (HLA-G), Killer Immunoglobulin-Like Receptor (KIR), and Human Leukocyte Antigen-C (HLA-C), which influence trophoblast invasion and spiral artery remodeling. This study aimed to assess differences in HLA-G, KIR, and HLA-C expression in the placental tissue of mothers with and without preeclampsia. Methods: This cross-sectional analytic study involved 22 pregnant women (11 with PE and 11 without) selected by purposive sampling at Prof. Dr. I.G.N.G. Ngoerah Hospital. Placental tissues obtained at delivery were preserved in formalin, processed into paraffin blocks, and sectioned for histological and immunohistochemical analysis. Expression of HLA-G, KIR, and HLA-C was assessed using standard staining protocols and categorized by intensity and frequency. Data were analyzed using SPSS version 25. Results: A total of 22 pregnant women were included in the analysis, consisting of 11 with preeclampsia and 11 without. Maternal characteristics did not show significant age differences (26.0 vs. 28.0 years; p = 0.41) or gestational age (35.0 vs. 34.0 weeks; p = 0.27), although parity was significantly lower in the preeclampsia group (p = 0.03). Bivariate analysis of immunological markers revealed that preeclampsia was significantly associated with low KIR expression (PR 4.67; 95% CI: 1.712–12.724; p = 0.001), high HLA-C expression (PR 4.50; 95% CI: 1.246–16.253; p = 0.003), and low HLA-G expression (PR 3.06; 95% CI: 1.285–7.300; p = 0.024). Conclusion: Low HLA-G expression, low KIR, and high HLA-C are significantly associated with an increased risk of preeclampsia.