PDCD1 and melanoma: A recent study revealed upregulation of PD-L1 expression by human and murine macrophages and DCs in both the tumor microenvironment and the draining lymph nodes, with PD-L1 expression by macrophages and DCs in the tumors of melanoma and ovarian cancer patients being associated with the response to immunotherapy using anti-PD-1 antibody alone or the combination of anti–PD-1 and anti-cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) antibodies [43].