CTLA4 and neoplasm: Furthermore, CD80 and CD86 are expressed on the surface of antigen-presentation cells (APCs) like dendric cells and monocyte-macrophages, while the non-hematologic tumor doesn’t express CD80 or CD86, so blockade of CTLA-4 is thought to stimulate T cell activation in the secondary lymphoid organs where naive T cells are co-stimulated and differentiate into effector or memory T cell, but not in the tumor microenvironment (24).