Real-time imaging reveals macrophages devouring live melanoma cells

Using intravital two-photon microscopy, researchers watched CD169-expressing macrophages in the skin’s hypodermis engulf live melanoma cells without T or B cells, a finding that depletion of these macrophages worsened tumor growth and that similar macrophage populations were found at human melanoma margins—suggesting a way to turn ‘cold’ tumors ‘hot’ and possibly enhance responses to immune checkpoint inhibitors.