Among the subtypes, SCLC-A tumors displayed higher expression of immunosuppressive receptors (FoxP3, PD2, and CTLA4) and lower levels of immune-promoting receptors (CD8), whereas SCLC-I tumors exhibited the highest immune cell infiltration, with notably increased T cells, NK cells, and macrophages (8, 124). This evidence concerns the gene CTLA4 and small cell lung carcinoma.