Ingram, Jessica R.Dougan, MichaelRashidian, MohammadKnoll, MarkoKeliher, Edmund J.Garrett, SarahGarforth, ScottBlomberg, Olga S.Espinosa, CamiloBhan, AtulAlmo, Steven C.Weissleder, RalphLodish, HarveyDougan, StephaniePloegh, Hidde L.2017-12-052017Ingram, J. R., M. Dougan, M. Rashidian, M. Knoll, E. J. Keliher, S. Garrett, S. Garforth, et al. 2017. “PD-L1 is an activation-independent marker of brown adipocytes.” Nature Communications 8 (1): 647. doi:10.1038/s41467-017-00799-8. http://dx.doi.org/10.1038/s41467-017-00799-8.http://nrs.harvard.edu/urn-3:HUL.InstRepos:34491867Programmed 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.en-USJournal Article2017-12-0510.1038/s41467-017-00799-8