In situ analysis of the inflammatory cell infiltrates in colon carcinomas and in the normal colon wall.

Inflammatory cells (lymphocytes, plasma cells, macrophages, mast cells and polymorphonucleated cells) forming infiltrates in the stroma of ten colon carcinomas were analysed in situ and compared with the cells of the normal colon wall. The cancer stroma contained a larger proportion of lymphocytes, while the number of IgA-containing plasma cells was markedly reduced compared to the normal colon mucosa from the resection edge. In both tissues the number of macrophages was much higher than the study of H & E stained routine preparations would suggest. The peritumoural cell infiltrates consisted of 47% lymphocytes, 19% plasma cells, 15% macrophages (including monocytes) and 5% granulated mast cells, while 15% of all inflammatory cells were polymorphonucleated (PMN). Necrotic areas of the tumours were dominated by a larger number of PMN and macrophages. Compared to the normal colon wall, the significant differences in cell composition and the accumulation of mononuclear cells (MC) at the cancer borders indicate that populations of cells are selectively attracted to the tumour site, although the factors responsible for the local cell reaction in cancer are still unknown.