CD8A and neoplasm: So the tumors derived Exos exhibit contradictory immune effects; sometimes they can decrease the proliferation of CD4 and CD8 T lymphocytes/NK cells or promote the differentiation of immunosuppressive cells such as Treg or myeloid cells and, at other times, Exos from tumor cells promotes tumor growth and metastasis by increasing the differentiation of inhibitory myeloid cells and decreasing NK cell activity.