ASSOCIATION OF DIFFERENT MACROPHAGE PHENOTYPES WITH INFILTRATING AND NON-INFILTRATING AREAS OF TUMOR-HOST INTERFACE IN COLORECTAL-CARCINOMA

At the tumor-host interface (interface) of well differentiated tubular y or tubulopapillary colorectal carcinomas infiltrative, poorly demarc ated and non-infiltrative, well boardered areas alternate. The composi tion of the inflammatory infiltrate within the desmoplastic stroma of the central tumor part and the interface was analyzed, particularly em phasizing differences between infiltrative and non-infiltrative areas of the interface. Of particular interest was the distribution of the f ollowing recently identified, functionally different human macrophage phenotypes. the 27E10-positive phenotype, an inflammatory macrophage, the 25F9-positive phenotype, a mature, resident macrophage and the RM3 /1-positive phenotype, associated with anti-inflammatory function. It was found that macrophages were the dominating cells in the inflammato ry infiltrate of both central tumor part and interface and that the nu mber of B-cells and NK-cells were negligible. The 27E10-positive pheno type revealed a strong association with infiltrative areas at the inte rface, whereas the resident macrophage together with the RM3/1 was ass ociated with sharply bordered tumor areas dominating within the tumor stroma, particularly in carcinomas with marked desmoplastic stroma res ponse. These findings suggest that different macrophage phenotypes, lo calized in different regions of the carcinoma, have different effects on tumor cells.