ARG1 and neoplasm: Small EV can reduce T‐cell membranes containing ARG1 CD3 zeta and CD3 epsilon chain expression level. In vivo and in vitro inhibition of CD4 + and CD8 + T cells proliferation. ARG1 can be transported to other sites, such as draining lymph nodes, to promote immunosuppression and accelerate tumor progression.ARG1 + EV can be endocytosis by DC cells, thus inhibiting the stimulating effect of DC cells on T cells.