IL4 and central nervous system cancer: On the other hand, exogenous factors include the infiltration of various immunosuppressive cells and the expression of related inhibitory molecules,[9] while macrophages constitute more than half of the immune cells infiltrating glioma, secreting immunosuppressive molecules like IL‐4, IL‐10, and SIRRα.[10] These molecules can effectively enable glioma cells to evade innate immune recognition, thus limiting the efficacy of adaptive immune responses.