Background: Tumor microenvironment (TME) contributes to the initiation and progression of low grade glioma (LGG); however, we are still unclear about the specifics of LGG's TME. Methods: In this article, we selected 161 LGG patients from the Cancer Genome Atlas (TCGA) as data, and calculated the percentage of tumor infiltrating immune cells (TICs) in LGG and the tumor purity of LGG through ESTIMATE and CIBERSORT calculation methods. Immune-related genes were screened out through Cox regression

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... nd protein-protein interaction (PPI) network. The data in Gene Expression Omnibus (GEO) was selected to screen out clinically relevant genes. After combining the two, CD3E is selected as the predictor. Finally, we conducted verification at the Affiliated Hospital of YouJiang Medical University for Nationalities (AHYMUN) center. Results: We found that the higher the expression of CD3E, the lower the purity of LGG tumors and the worse the prognosis of patients. Gene Set Enrichment Analysis (GSEA) showed that genes in the high-expressing CD3E group are mainly involved in immune-related activities. This suggests that CD3E may be responsible for regulating LGG's TME and tumor purity.Conclusion: In short, the tumor purity of LGG has a considerable impact on clinical, genomic and biological status. The expression level of CD3E may help doctors evaluate the prognosis of LGG patients and develop personalized immunotherapy plans for patients. Evaluating the ratio of different tumor purity and the new role of CD3E may provide additional insights into the complex role of the LGG microenvironment and clinical treatment.