INTRAEPITHELIAL LYMPHOCYTES VS. COLORECTAL NEOPLASTIC-CELLS - WHO IS WINNING THE APOPTOTIC BATTLE

Intraepithelial lymphocytes (IELs) and Intraepithelial apoptotic granu les (AGs) are found in the vast majority of colorectal adenomas, less frequently in incipient carcinomas and occasionally in advanced colore ctal carcinomas. In colorectal adenomas, the activated and cytotoxic I ELs undergo apoptosis by a Fas-FasL mechanism. In advanced invasive ca rcinomas lacking IELs, that mechanism cannot be activated. On the othe r hand, the peritumoural lymphocytes which surround some advanced inva sive carcinomas may abrogate to-be-metastatic tumor cells, as treated cancer patients with peritumoural lymphocytes have a better 5-years' s urvival than those without that peritumoural barrier. In colorectal ad enomas the host reaction (IELs) dysplastic cells Fas-dependent confron tation seems to prevent rapidly proliferating adenomas from becoming r apidly invasive carcinomas, since that process takes 10 to 20 years to evolve.