According to the medical data, tumour-infiltrating PD-L1+ T cells can act on PD-1+ macrophages and suppress M1 polarization by reducing NF-κB and signal transducer, as well as activator of transcription (STAT) 1 phosphorylation, but induce M2 polarization by increasing STAT6 phosphorylation. The gene discussed is STAT6; the disease is neoplasm.