More Treg cells are found in colon cancer stroma compared with normal colonic mucosa. (A) Ex vivo FACS staining of lymphocytes from normal colonic mucosa and from colon tumours. The percentage shown is that of CD25+^hi lymphocytes in the CD4+ population. (B) Percentage of CD4+ CD25+ T cells in the tumour and the normal colonic mucosa of colorectal cancer patients (n = 33). (C) Percentage of CD4+ CD25+ T cells in the tumour of patients with Dukes' A and B disease (n = 19) versus Dukes' C and D disease (n = 14).