CD4 and melanoma: Alternatively, macrophages capable of suppressing CD4+ and CD8+ T cell proliferation have been differentiated from monocytes cultured in conditioned media from both metastatic and non-metastatic human melanoma cell lines (94), and IL-10, which can be secreted at high levels by melanomas (95), has been shown to promote the trans-differentiation of monocyte-derived DC into tolerogenic CD14+ BDCA3+ macrophage-like cells similar to those known to be enriched in melanoma metastases (96).