Because TAMs in melanoma comprise a heterogeneous, mainly immunosuppressive population (9, 23), and because repolarization of TAMs into the activated subtype by immunomodulatory drugs has been reported to significantly suppress melanoma growth in a spontaneous mouse melanoma model (8), we hypothesized that one of the targets for nivolumab in melanoma is activated CD163+ TAMs. Here, CD163 is linked to melanoma.