ARG1 and neoplasm: In addition to this, it was reported that normal neutrophils may suppress the function of T-cells, and activated neutrophils increase the level of arginase 1, which leads to suppression of T-cells.16 In addition to contributing to the immune suppression of T-cells, neutrophils may also show characteristics that support tumors such as inducing angiogenesis and increasing tumor metastasis by raising the expression of matrix metalloproteinase.9