(Nature Publishing Group UK, 2017) Ingram, Jessica R.; Dougan, Michael; Rashidian, Mohammad; Knoll, Marko; Keliher, Edmund J.; Garrett, Sarah; Garforth, Scott; Blomberg, Olga S.; Espinosa, Camilo; Bhan, Atul; Almo, Steven C.; Weissleder, Ralph; Lodish, Harvey; Dougan, Stephanie; Ploegh, Hidde L.
Programmed death ligand 1 (PD-L1) is expressed on a number of immune and cancer cells, where it can downregulate antitumor immune responses. Its expression has been linked to metabolic changes in these cells. Here we develop a radiolabeled camelid single-domain antibody (anti-PD-L1 VHH) to track PD-L1 expression by immuno-positron emission tomography (PET). PET-CT imaging shows a robust and specific PD-L1 signal in brown adipose tissue (BAT). We confirm expression of PD-L1 on brown adipocytes and demonstrate that signal intensity does not change in response to cold exposure or β-adrenergic activation. This is the first robust method of visualizing murine brown fat independent of its activation state.
