Endometrial Staining of CD56 (Uterine Natural Killer), BCL-6, and CD138 (Plasma Cells) Improve Diagnosis and Clinical Pregnancy Outcomes in Unexplained Infertility and Recurrent IVF Failures: Standardization of Diagnosis with Digital Pathology

Abstract

In women with unexplained infertility (UI) and recurrent in vitro fertilization (IVF) failures, the etiology is often unclear. Endometrial immune perturbations and the use of immune markers associated with these dysregulations are of great interest in the diagnosis and treatment of UI. However, reliable biomarkers and standardized quantification methods are lacking. Here, to address endometrial immune dysregulation in UI patients with recurrent IVF failures, we performed endometrial tissue sampling and immunostaining of CD56 (uNK), CD138, and BCL-6. Of these cases, 57.9% had positive CD56 in the endometrial stroma, while 46.1% had positive BCL-6 in the glandular epithelium, and 14.5% of the cases were found to be positive for CD138. Combined staining rates were 60.5%, 68.4%, and 71.05% for (CD56 or BCL-6), (CD56 or CD138), and (CD56, BCL-6, or CD138), respectively. There was a significant correlation between CD56 and BCL-6 positivity, while CD138 positivity was an independent parameter. After the recommended targeted therapy, pregnancy rates were found to increase from 58.5% to 61.6% and 73.8% in CD56-positive, (CD56- or BCL-6-positive), and (CD56-, BCL-6-, or CD138-positive) cases, respectively. Notably, a retrospective evaluation of digital pathology and light microscopy results showed a significant correlation. This study suggests that the examination of CD56, BCL-6, and CD138 in the same endometrial sample may be an effective method in determining the etiology of UI and reaching an early diagnosis and treatment options. Moreover, digital pathology can be used in the evaluation of CD56 and BCL-6 to provide objective, rapid, and reliable results.

Keywords: BCL-6; CD138; CD56 (uNK); endometriosis; endometritis; recurrent IVF failures; unexplained infertility (UI).

Figure 1

The semiquantitative analysis of the endometrium by conventional light microscopy (LM). (A) Representative examples of positive (≥6%) and negative (<6%) cells with immunohistochemical staining for CD56 in the stroma. (B) Representative examples of HSCORE grading of positive (≥1.4) and negative (<1.4) cells with immunohistochemical staining for BCL-6 in the glandular epithelium. (C) Representative examples of CD138 positivity and negativity in the stroma. (D) H&E staining of corresponding positive IHC sections in (A–C). (E) Irrelevant neuroendocrine tumor section in A and lymph node sections in B and C were used as positive controls. The pictures are at the same magnification.

Figure 2

Digital pathology analysis of the endometrium by 3DHISTECH CaseViewer. (A) Representative examples of positive cells with digital imaging for CD56 in the stroma. (B) Representative examples of HSCORE grading of positive cells with digital imaging for BCL-6 in glandular epithelium. The pictures are at the same magnification.