Immunohistochemical Analysis of PD-1 and FOXP3 in Tumor-Infiltrating Lymphocytes in Human Gliomas

Introduction Despite the growing advances in molecular research and therapeutics, gliomas continue to be highly invasive and progressive tumors. There is still a need for the development of reliable prognostic biomarkers for effective therapeutic intervention. This study aims to investigate the extent of immunosuppression in glial tumors by analyzing the clinical significance of the expressions of PD-1 and FOXP3 in gliomas. Methods This is a retrospective study from 52 glioma patients who underwent surgery. Immunohistochemistry (IHC) for PD-1 and FOXP3 was performed on paraffin-embedded tissue sections manually and their expressions were noted. Data on IDH1 mutational status and mitotic index was collected and statistically analyzed. Results Immunohistochemical analysis showed that out of 52 cases, 71.15% (37/52) demonstrated cytoplasmic positivity for PD-1 and 73.1% (38/52) of the cases for nuclear FOXP3 expression. Statistical analysis suggested that elevated PD-1 and FOXP3 expressions were significantly correlated with tumor grade and increased mitotic index (P<0.05 for both the markers). Conclusion Concurrent use of checkpoint inhibitors along with other treatment modalities is being studied in a variety of solid tumors. Expressions of negative immune regulators like PD-1 and Foxp3 can pave way for a better understanding of the extent of immunosuppression in the glial tumor environment, which is imperative to formulate new therapeutic approaches.