IL6 and central nervous system cancer: In addition to the infiltrating immune cells, glioma cells express immune suppressive molecules such as interleukin-6, interleukin-10, TGF-β, LDH5, galectin-1 (gal-1), and prostaglandin-E which reprogram the infiltrating immune cells to a pro-tumor phenotype (Figure 2; Van Meir, 1995; Huettner et al., 1997; Crane et al., 2012; Perng and Lim, 2015).