P-352 Evaluation of CD25 and CD69 activation markers expression on peripheral blood cells subpopulations in endometriosis patients
Authors: Abramiuk M , Dymanowska-Dyjak I , Grywalska E , Polak G 
Published: June 2023

Abstract

Study question
We aim to determine the percentages of CD25-positive and CD69-positive lymphocytes in peripheral blood of endometriosis (EMS) patients.

Summary answer
Higher percentages of lymphocytes expressing CD69 and CD25 markers in EMS and their correlation with the severity of the disease, indicate persistent activation of lymphocytes

What is known already
Exposure to antigens causes activation markers to appear on the surface of lymphocytes. Among them, we can distinguish early and late activation markers. The earliest one is CD69, which is expressed upon activation by the TCR receptor. CD69 plays a role in the proliferation and survival of activated T lymphocytes. CD25 is a moderate late activation marker, considered the most important marker of cellular response activation. The significance of CD69 and CD25 expression by T cells in endometriosis has not yet been determined. Increased CD69 expression on various lymphocyte subsets in peritoneal fluid in EMS has been reported.

Study design, size, duration
Within this prospective study between January 2016 and August 2018 immune diagnostics of the number of CD25-positive and CD69-positive lymphocytes in peripheral blood of EMS patients (firstly diagnosed during laparoscopy and confirmed histopatologically) and non-EMS controls were performed using flow cytometry analysis. Total number of 74 subjects were included in the study. All patients signed written informed consent before their enrollment in the study.

Participants/materials, setting, methods
We enrolled 54 subjects with previously untreated endometriosis and 20 healthy age-matched controls. Peripheral blood was collected from control patients to assess the immunophenotype of lymphocytes and measure expression of activation markers Cd25 and CD69 on several subtypes B and T lymphocytes. Diagnosis and assessment of the stage of the EMS was established during laparoscopy using rASRM score. Differences were considered statistically significant with a p &lt; 0.05.

Main results and the role of chance
Significantly higher expression of the CD25 and CD69 antigen was found in both CD3+ T, CD4+ T and CD8+ T cells as well as CD19+ B cells. In each of the studied groups, a significance level of p &lt; 0.001 was obtained. There was a weak positive correlation between the percentage of CD4+CD25+ T cells and the stage of endometriosis (R = 0.357; p = 0.008) and negative correlations between the percentage of endometriosis and the percentage of CD3+CD69+ T cells (R = −0.554; p &lt; 0.001), T CD4+CD69 + (R = −0.554, p &lt; 0.001) and T CD8+CD69 + (R = −0.553, p &lt; 0.001). The expression of activation markers, CD25 and CD69 antigens in patients suffering from endometriosis with accompanying clinical symptoms was also evaluated. n the group of patients with endometriosis accompanied by infertility or pelvic pain, no statistical differences in the expression of CD25 and CD69 antigens were observed. The only clinical condition coexisting with statistically different expression of activation markers is adhesion disease accompanying endometriosis - a statistically significantly lower percentages of T CD3+CD69 + (p = 0.002), T CD4+CD69 + (p = 0.002) and T CD8+CD69 + (p = 0.002).

Limitations, reasons for caution
Small sample size is an important limitation of this study. In addition, evaluating immunological analysis only in serum samples does not let us drive any conclusions on the local changes of endometriosis lesions.

Wider implications of the findings
Clinical interpretation of changed expression of CD69 and CD25 in EMS could be useful in evaluating mechanisms of cellular activation, peripheral tolerance and immune imbalance involved in pathogenesis of endometriosis. Further studies to understand mechanisms underlying correlation between stage of the disease and expression of CD69 should be considered.

Trial registration number
not applicable