Increased PD-L1 and IDO1 levels are commonly linked to immunosuppressive activities of macrophagic myeloid-derived suppressor cells (MDSCs), neutrophils, granulocytes, and monocytes.27 Moreover in lung tuberculosis, IDO1+ macrophages have been associated with suppressive functions.16 This suggests that the Macro_03_M1 subcluster in bacterial infections resembled macrophagic MDSCs (M-MDSCs), highlighting its potential role in immune suppression and the maintenance of bacterial infections, potentially contributing to disease progression. This evidence concerns the gene IDO1 and bacterial infectious disease.