Conclusions
Anal dysplastic lesions are accompanied by an inflammatory lymphocytic infiltrate expressing CD8 and PD-1, more frequent in high-grade lesions. These results highlight the involvement of the PD-1/PD-L1 pathway in the natural history of anal dysplasia.
Methods
Patients followed in the AIN3 cohort were routinely sampled. For each selected sample, an immunohistochemical study was performed with anti-CD8, PD-1, PD-L1 antibodies. The presence and distribution of CD8+ lymphocytes, and the presence of PD-1+ lymphocytes and PD-L1+ epithelial cells were assessed. The comparison of these characteristics was performed between the HSIL and LSIL groups.
Results
33 patients were included and 78 samples selected (60 HSIL and 18 LSIL). CD8+ lymphocytes were observed more frequently in HSIL versus LSIL in the lamina propria or intra epithelial (respectively 90% vs. 60%, p = 0.01; and 62% vs. 33%, p = 0.04). PD-1+ lymphocytes were observed more frequently in HSIL versus LSIL (41% vs 11%, p = 0.03). There was no difference between HSIL and LSIL for PD-L1+ epithelial cells. Conclusions: Anal dysplastic lesions are accompanied by an inflammatory lymphocytic infiltrate expressing CD8 and PD-1, more frequent in high-grade lesions. These results highlight the involvement of the PD-1/PD-L1 pathway in the natural history of anal dysplasia.