Consistent with the observations in Apcmin/+ mice, P. anaerobius administration in AOM-induced CRC resulted in an increase in MDSCs (P < 0.05; Extended Data Fig. 1e) along with a decrease in functional T cells (IFN-γ+CD8+ and IFN-γ+CD4+; both P < 0.05; Extended Data Fig. 1f) compared with the control mice, as determined by flow cytometry analysis. This evidence concerns the gene CD8A and colorectal carcinoma.