CD4 and colorectal carcinoma: Together with reports from the literature that tumour-infiltrating CD4-positive T cells can be detected in MSI-H as well as in MSS CRC stroma and at lower number also in the CRC epithelium (Dolcetti et al, 1999), these data show that the vast majority of FOXP3-positive T cells infiltrating CRC stroma and epithelium represent CD4-positive cells and not activated CD8-positive effector cells.