Multiphoton autofluorescence imaging of immune cells in cancer

Current methods to assess immune cell function use labels that are limiting for time-course studies of immune cell behavior in tumors. Here, we use multiphoton imaging of NAD(P)H and FAD, co-enzymes of metabolism, in T cells and macrophages within the tumor microenvironment. T cells alter their metabolism in response to tumor-like pH, glucose, and lactic acid levels, while macrophages alter their metabolism during tumor-stimulated migration. These results indicate that multiphoton autofluorescence imaging is a powerful label-free method to monitor immune cell metabolism within single cells in the tumor microenvironment.