Decreased HLA-C1 alleles in couples of KIR2DL2 positive women with recurrent pregnancy loss.

Specific killer cell immunoglobulin-like receptor (KIR) in women with recurrent pregnancy loss (RPL) and HLA ligands in couples invoke a susceptibility to RPL. However, the relationship between KIR2DL2 and its cognate ligand HLA-C1 has not been explored. In this prospective cohort study, 160 Caucasian women with RPL and 99 partners were included. KIR/HLA-C typing, NK assay, Th1/Th2 intracellular cytokine ratios, 25-(OH)-vitamin D level, and the presence of autoantibodies were analyzed. KIR2DL2 positive women (P = 0.023) and their partners (P = 0.017) had lower allele frequencies of HLA-C1 than those of KIR2DL2 negative women. KIR2DL2 positive women had significantly lower genotype frequency of HLA-C1C1 as compared to the North American Caucasian population controls (P < 0.05). In the partners of KIR2DL2 positive women, there was a substantially higher frequency of HLA-C2C2 than controls (P = 0.016). Besides, KIR2DL2 negative women had a higher prevalence of anti-ssDNA antibody as compared with that of KIR2DL2 positive women (P = 0.043). There were no differences in the distribution of HLA-C genotypes based on KIR2DL2, regardless of pregnancy outcome in women with RPL and their partners while on immunomodulation treatment. In conclusion, decreased ligands for inhibitory KIRs (inhKIR) could lead to insufficient inhibition of maternal uterine NK cells toward the trophoblast, thereby contributing to the pathogenesis of RPL. Specific KIR and HLA-C genotyping may predict the reproductive outcome of women with RPL.

PD-1 and PD-L1 expression on T-cell subsets in women with unexplained recurrent pregnancy losses.

PROBLEM: Does programmed death-1 (PD-1)/programmed death ligand-1 (PD-L1) expression on the T-cell subsets such as T helper (Th) 1, Th17, and Treg cells differentiate women with recurrent pregnancy losses (RPL) from normal fertile women? METHOD OF STUDY: The study was designed as a prospective cohort study. Forty-five women with two or more RPL of unknown etiology and twenty fertile women who had at least one or more live-born infants were enrolled prospectively from Jan 2017 to Jul 2019. PD-1 and PD-L1 expression on T-cell subsets were measured by flow cytometric analysis. RESULTS: The proportions of PD-1+ Th1 (CD4+ /IFN-γ+ /CD279+ and CD4+ /TNF-α+ /CD279+ ) and PD-1+ Th17 cells (CD4+ /IL17+ /CD279+ ) were significantly lower in RPL group than those of controls (P < .05, respectively). The proportion of PD-1+ Tregs (CD4+ /CD25+ /CD127dim/- /CD279+ ) in RPL group was not different from that of controls. The proportion of PD-L1+ Th17 cells (CD4+ IL17+ CD274+ ) was significantly lower as compared with that of /controls (P < .05). However, the proportions of PD-L1+ Th1 (CD4+ /IFN-γ+ /CD274+ and CD4+ /TNF-α+ /CD274+ ) and PD-L1+ Treg (CD4+ /CD25+ /CD127dim/- /CD274+ ) cells were not different between the RPL group and controls (P > .05, respectively). In Th1, Th17 and Treg cells, the proportions of PD-L1+ (CD274+ ) cells were significantly higher than those of PD-1+ (CD279+ ) cells in both RPL group and controls (P < .05, respectively). CONCLUSION: PD-1 and PD-L1 expressions on Th17 cells as well as PD-1 expression on Th1 cells were significantly downregulated in women with RPL, which may lead to increased Th1 and Th17 immunity, and imbalance between Th17, Th1, and Treg cells in women with RPL.