While Foss et al. [19] considered it a limitation to the specificity of the tracer, it seems plausible that – depending on species, pathogen and/or the experimental infection condition—elevated TSPO-specific PET in anatomically unaffected lung is indicating a biologically pertinent involvement of activated macrophages as part of an organ-specific infection response that may be independent of lesion formation per se. Here, TSPO is linked to infection.