CD4 and neoplasm: The results showed that the expression level of SNCA correlated negatively with the tumor purity (r = − 0.415, p = 1.14E-42) and positively with CD8+ cell (r = 0.353, p = 4.25E-30), CD4+ cells (r = 0.326, p = 3.475E-25), macrophages (r = 0.462, p = 3.81E-53), neutrophils (r = 0.319, p = 6.91E-24), and dendritic cells (r = 0.345, p = 6.67E-28) (Fig. 5A).