LAUSR

Gram‐negative Pseudomonas bacteria are largely harmless saprotrophs, but some species can be potent pathogens of both plants and mammals. Macrophage migration‐inhibitory factor (MIF) and its homologue D‐dopachrome tautomerase (D‐DT, also referred to as MIF‐2) are multifunctional proteins that in addition to their intracellular functions also serve as extracellular signalling molecules (cytokines) in orchestrating mammalian immune responses. It recently emerged that plants also possess MIF‐like proteins, termed MIF/D‐DT‐like (MDL) proteins. We here provide a comparative cross‐kingdom view on the immunomodulatory role of MIF and MDL proteins during Pseudomon as infections in mammals and plants. Although in both kingdoms the lack of MIF/MDL proteins is associated with a reduction in bacterial load and disease symptoms, the underlying molecular principles seem to be different. We provide a perspective for future research activities to unravel additional commonalities and differences in the MIF/MDL‐mediated adjustment of antibacterial immune activities.