IDO1 and squamous cell carcinoma: Examples are IL-10+ B cells in tumor tissues of gastric cancer [20], squamous cell carcinoma of the tongue [21] and ascites from ovarian cancer [22]; IgA+ CD138+ PD-L1+ IL-10+ B cells in prostate cancer [23]; CD5high CD24−/+ CD27high/+ CD38dim PD-1high B cells producing IL-10 in human hepatocellular carcinoma [9]; Granzyme B+ CD38+ CD1d + IgM + CD147+ B cells expressing IL-10 and IDO in breast, cervical and ovarian carcinomas [19].