Expression and Prognostic Significance of PD-1/PD-Ls in Breast Cancer Draining Lymph Nodes

Written by: Zahra Mansourabadi

Abstract

Background: Tumor-draining lymph nodes play a pivotal role in orchestrating immune cell trafficking and initiating antitumor responses. Among immunoregulatory molecules, programmed cell death protein 1 (PD-1) has emerged as a central mediator in tumor-induced immunosuppression. Methods: Lymph node samples were freshly collected from BC patients undergoing surgery. Mononuclear cells were isolated and analyzed by flow cytometry for surface markers CD45, PD-1, PD-L1, and PD-L2. Data were analyzed using FlowJo v10.8.1. Results: PD-1 was detected on 9.48 ± 5.19% of CD45+ cells, whereas PD-L1 and PD-L2 were expressed at lower levels (1.73 ± 0.85% and 1.68 ± 0.84%, respectively). Despite a significant reduction in the percentage of CD45+ lymphocytes, the frequencies of PD-1+ and PD-L2+ subsets were significantly elevated in patients with poorly-differentiated and advanced-stage tumors (P<0.05). Additionally, the frequency of PD-1+ lymphocytes was significantly higher in patients with the triple-negative tumors (P=0.014) and in those negative for estrogen and progesterone receptor (P=0.001).