CD4 and melanoma: Melanoma-derived vesicles are also a tumour antigen source with ability to induce epitope cross-presentation in dendritic cells [25] and even activate cytotoxic T-lymphocytes against them [13], but they have shown the capacity to support expansion of CD4+CD25highFOXP3+ regulatory T cells (Treg), while eliminating activated CD8 + antitumor effector cells [26].