Depending on the predominant immune cell type, either a tumor-inhibiting effect (acute inflammation by CD8 lymphocytes (Th1) or M1 macrophages) or a Th2-driven tumor-promoting effect (chronic inflammation by M2 macrophages, regulatory T cells, or immune checkpoints such as programmed cell death protein 1 (PD-1) or its ligand (PD-L1) can result. The gene discussed is PDCD1; the disease is neoplasm.