PD-L1 Expression and Tumor Microenvironment Dynamics in Diffuse Large B-Cell Lymphoma: Immunophenotypic Insights

Area of Science:

• Oncology
• Immunology
• Pathology

Background:

• Diffuse large B-cell lymphoma (DLBCL) is a heterogeneous B-cell non-Hodgkin lymphoma (NHL).
• The programmed death 1 (PD-1)/programmed death-ligand 1 (PD-L1) pathway is critical for tumor immune evasion.
• The prognostic and diagnostic significance of PD-1/PD-L1 in DLBCL requires further elucidation.

Purpose of the Study:

• To investigate the diagnostic and prognostic relevance of PD-1 and PD-L1 expression in DLBCL.
• To correlate PD-1/PD-L1 expression with clinicopathological features and tumor microenvironment markers.
• To explore the role of immune checkpoints in DLBCL pathogenesis and immune evasion.

Main Methods:

• Retrospective analysis of 66 DLBCL cases diagnosed between 2017 and 2024.
• Immunohistochemistry for PD-L1, PD-1, CD4, CD8, and CD68 on formalin-fixed, paraffin-embedded tissues.
• Statistical correlation of marker expression with clinical data and histopathological features.

Main Results:

• Tumoral PD-L1 expression was infrequent (9.1%), but immune cell PD-L1 positivity was common (59.1%).
• PD-1 was observed in tumor samples and 40.9% of stromal immune cells.
• Tumoral PD-L1 correlated with anaplastic variants (P=0.015); PD-1 in immune cells associated with female gender (P=0.044); CD68 correlated with lower Ann Arbor stage (P=0.040).

Conclusions:

• PD-L1 and PD-1 expression patterns in DLBCL suggest roles in immune evasion and prognosis, especially in anaplastic subtypes.
• The tumor microenvironment, including macrophage infiltration (CD68), influences DLBCL progression.
• Further research is warranted to validate these findings and explore therapeutic implications of PD-1/PD-L1 blockade in DLBCL.