Killer-cell immunoglobulin-like receptors associated with polycystic ovary syndrome

•In this case-control study, KIR and its HLA ligands influenced the development of PCOS.•KIR3DS1-Bw4 and homozygosis of KIR2DS4-del showed susceptibility to the PCOS (Pc = 0.002, OR = 2.90; Pc = 0.0002, OR = 3.316, respectively).•KIR2DS4-full (Pc = 0.0004, OR = 0.320) was a protective factor for PCOS.•KIR3DS1-Bw4-80 T had higher frequency in PCOS patients than controls, however, significance was lost after Bonferroni correction (P = 0.04, Pc = 0.08, OR = 2.88). Polycystic ovary syndrome (PCOS) affects the endocrine system and is associated with low-grade inflammation. Natural killer (NK) cells are involved in the defense of the female reproductive tract, folliculogenesis, ovulation and the menstrual cycle. The killer-cell immunoglobulin-like receptors (KIR) on the surface of NK cells modulate the activation and function of these cells after interacting with human leukocyte antigen (HLA) class I ligands. The objective of this study was to evaluate the possible association of the KIR and their HLA ligands with polycystic ovary syndrome. Ninety-three patients with PCOS according to the Rotterdam criteria and 104 healthy controls were included in this study. The HLA class I and KIR genotypes were determined using a PCR-SSO technique, rSSO Luminex®. In order to assess whether the distribution of the HLA and KIR genotypes was in Hardy-Weinberg equilibrium, Arlequin 3.1 software was used. The frequency distributions in the two study groups were compared using the chi-squared statistic with Yates´s correction using Open Epi software. The higher frequencies of KIR3DS1-Bw4 (41% vs. 19%, Pc = 0.002; OR = 2.90) and homozygotic KIR2DS4-del (54% vs. 26%, Pc = 0.0002; OR = 3.316) in patients compared with controls suggest they confer susceptibility to PCOS. A lower frequency of KIR2DS4-full was observed in patients (43% vs. 70%, Pc = 0.0004, OR = 0.320). KIR and its HLA ligands were associated with the development of PCOS in the studied population.