In the present study, immunohistochemistry for representative mismatch repair (MMR) enzymes, an alternative method to detect MSI, revealed no significant increase of intraepithelial CD8+ T cells in cases with a loss of MMR eznymes, and no significant increase in right-sided colon cancer, where the incidence of MSI is high. This evidence concerns the gene CD8A and malignant colon neoplasm.