PD-1/PD-L1 expression in anal squamous intraepithelial lesions

Area of Science:

• Immunology
• Oncology
• Pathology

Background:

• The PD-1/PD-L1 pathway regulates anti-tumor immunity in various cancers.
• PD-1 and PD-L1 expression in anal squamous intra-epithelial lesions (LSIL/HSIL) remains uncharacterized.

Purpose of the Study:

• To investigate the expression and distribution of CD8+ lymphocytes, PD-1+ lymphocytes, and PD-L1+ epithelial cells in anal LSIL and HSIL.
• To compare these immune markers between LSIL and HSIL to understand their role in anal dysplasia progression.

Main Methods:

• Immunohistochemical analysis of CD8, PD-1, and PD-L1 on 78 anal lesion samples (60 HSIL, 18 LSIL).
• Assessment of the presence and distribution of CD8+ lymphocytes, PD-1+ lymphocytes, and PD-L1+ epithelial cells.
• Statistical comparison of immune marker expression between HSIL and LSIL groups.

Main Results:

• CD8+ lymphocytes were significantly more frequent in HSIL compared to LSIL (lamina propria: 90% vs. 60%; intraepithelial: 62% vs. 33%).
• PD-1+ lymphocytes were also significantly more frequent in HSIL than LSIL (41% vs. 11%).
• No significant difference in PD-L1+ epithelial cell expression was observed between HSIL and LSIL.

Conclusions:

• Anal dysplastic lesions feature an inflammatory infiltrate of CD8+ and PD-1+ lymphocytes, which is more pronounced in high-grade lesions.
• The findings indicate the involvement of the PD-1/PD-L1 pathway in the pathogenesis and progression of anal dysplasia.