To pinpoint how PLCG2 induced the formation of the CRC immunosuppressive microenvironment and facilitated tumor immune escape, we constructed subcutaneous tumor models with the MC38 cell line and collected tumor tissues for flow cytometry, which demonstrated that knockdown of PLCG2 significantly promoted total CD8+ T -cell infiltration, and also induced the infiltration of GZMB+CD8+ T cells, PRF1+CD8+ T cells, IFN-γ+CD8+ T cells and TNF-α+CD8+ T cells, and inhibited PD-1+CD8+ T cell infiltration. The gene discussed is CD8A; the disease is neoplasm.