Tertiary lymphoid structures in endometriosis

OBJECTIVE: To determine whether tertiary lymphoid structures (TLSs), which reflect organized immune cell aggregates present in non-lymphoid tissues, are consistent features of endometriosis lesions. DESIGN: Detailed histopathological analysis of endometrial and lesion tissue from patients with endometriosis and controls was performed. Multiplex immunofluorescence on select samples was then conducted to identify canonical cell populations present within TLSs: CD3+ and CD8+ T-cells, CD79a+ B-cells, CD208+ dendritic cells, CD21+ follicular dendritic cells, and PNAd+ high endothelial venules. PATIENT(S): Patients with histologically confirmed endometriosis (N = 113; 44.3 ± 6.0) and control individuals (N = 110; 44.6 ± 7.1). INTERVENTION: Not applicable. MAIN OUTCOME MEASURE(S): Detection of TLSs as characterized by the presence of all canonical cell types that constitute TLS and structure morphology. RESULT(S): Of the selected samples (N = 18; 6 ectopic/eutopic/control), mature TLSs were identified in 3 ectopic tissue samples present on the ovary and fallopian tube, with immature TLSs (lacking follicular dendritic cell networks and high endothelial venules) present throughout eutopic and control endometrial samples. CONCLUSION: These findings demonstrate the presence of TLSs across various endometriosis phenotypes, prompting further research into their significance within disease pathophysiology and the prognostic implications for patients.