Immunohistochemical analysis of the relationship between CEA localization and mononuclear cell infiltration in human...

Thirty cases of colorectal adenocarcinoma were immunohistochemically examined to clarify the relationship between the degree of differentiation of cancer cells reflected by the mode of CEA localization and the infiltration pattern of mononuclear cells in the carcinoma tissues. Leu 1+, Leu 2a+, Leu 3a + 3b+ T lymphocytes, Leu 7+ cells, and IgA-containing plasma cells tended to be distributed more in areas where CEA was localized over the entire surface of the cancer cells or in their surrounding stroma than where CEA was located along the apical surface or within the cytoplasm. Carcinoma cells with the pattern of CEA staining at the former site were previously shown to be less differentiated than those at the latter. There were also CEA-containing phagocytes which were often observed where T cells and IgA plasma cells had aggregated. We speculated that the dedifferentiation of cancer cells might cause the host immune response, especially the cellular immunity, in malignant lesions.