Immunohistochemical Characterization of the Immune Response in Chronic Endometritis Caused by Chlamydia trachomatis

In 2020, 128.5 million new chlamydia infections were reported worldwide in adults aged 15-49 years. Notably, the prevalence of <i>Chlamydia trachomatis</i> infection in pregnant women varies between 2% and 35%, correlating with increased risks of low birth weight, preterm birth, and neonatal death. <i>C. trachomatis</i> is a leading preventable cause of miscarriage. Recurrent first-trimester pregnancy loss can be induced by asymptomatic chlamydia infection through the immune response. In this study, we performed immunohistochemical characterization of the immune response in endometrial tissue biopsies from women diagnosed with chronic endometritis caused by <i>C. trachomatis</i>. Hematoxylin and eosin staining was used for histological evaluation of endometrial biopsies, and immunohistochemical detection was performed for the following markers: CD138, CD45, CD3, CD4, CD8, CD20, CD56, and CD68. As a result, we observed the presence of edematous tissue with hemorrhage; we also observed a heightened inflammatory response with the presence of plasma cells, CD4 and CD8 T lymphocytes, B lymphocytes, NK cells, and macrophages. The findings described here can help better understand the disease and its histopathological diagnosis.