Human leukocyte antigen-G is expressed by the eutopic and ectopic endometrium of adenomyosis

OBJECTIVE: To compare the expression of human leukocyte antigen-G (HLA-G) in endometrial samples from patients with and without adenomyosis. DESIGN: Laboratory study using human tissue. SETTING: University hospital. PATIENT(S): Thirty-four patients with adenomyosis and 11 with myoma of the uterus. INTERVENTION(S): Human leukocyte antigen-G protein expression and localization with immunohistochemistry. MAIN OUTCOME MEASURE(S): Quantitative analysis of HLA-G protein expression, according to H-score. RESULT(S): A statistically significant difference was noted in HLA-G expression between the glandular cells of eutopic and ectopic endometrium (Mann-Whitney test, 412). The H-score of the negative control was 0.05 +/- 0.03 (mean +/- SD). In stromal cells, we observed a statistically significantly higher expression of HLA-G in eutopic endometrium than in ectopic endometrium (Mann-Whitney test, 169), whereas the H-score of the negative control was 0.05 +/- 0.02. A statistically significant correlation was found between HLA-G expression in ectopic and eutopic endometrium in patients with adenomyosis, both in glands (r = 0.89) and in stroma (r = 0.78). CONCLUSION(S): Patients with adenomyosis had HLA-G expression in eutopic and ectopic endometrial cells. This could be an explanation for the cells' ability to escape from the hosts' immunosurveillance and to survive without being eliminated by the immune system.