CD8A and colorectal neoplasm: ,54–56 For instance, indole-3-lactic acid has been reported to enhance CD8+ T cell-mediated immune responses against colorectal tumors, while IPA has demonstrated protection against radiation toxicity in mice without precipitating tumor growth.18,57 However, the specific reasons why I3A did not protect colon cancer cells in culture may be attributed to complex interactions with tumor cells.