CD4 and polyp of colon: When AOM-3DSS-induced colonic polyp-derived MHC-II−Gr1+ cells were co-cultured with splenic CD4+ T cells, T cell proliferation was suppressed by these tumor-infiltrating Gr1+ cells from WT mice, while Gr1+ cells from Clec7a−/− mouse polyps suppressed T cell population only weakly (Fig. 3k).