IL-4 may also inhibit the cell-mediated immune response by downregulating the expression of Th1 cytokines, such as IFN- γ and IL-2, and by decreasing the quantity and quality of the CD8+ T-cell response in the tumour microenvironment.2R allele has been shown to enhance the IL-4 production or activity by T cells [12]. This evidence concerns the gene IL4 and neoplasm.