Credit: Courtesy of Janis Taube, Johns Hopkins
Multispectral immunofluorescence showing the interface between Merkel cell tumor cells (orange) and host immune cells (yellow marks CD8+ lymphocytes, red marks CD68+ macrophages). Cell-surface PD-L1 expression (green) is observed on macrophages, lymphocytes and tumor cells, adjacent to PD-1 expression (white) on lymphocytes.