An immunophenotypic study of the inflammatory cell populations in colon adenomas and carcinomas.

There is increasing interest in the host immunologic response to colon carcinoma as immunotherapeutic techniques are being developed. We studied the inflammatory cells in 27 specimens of normal mucosa, 16 hyperplastic polyps, 21 tubular adenomas, 19 tubulovillous adenomas, 12 villous adenomas, and 17 invasive carcinomas using immunohistochemical techniques in paraffin-embedded tissue. UCHL-1-positive T-cells predominated in the lamina propria of all specimens. In polyps and carcinomas, reactive lymphoid follicles composed of L26-positive B-cells, and UCHL-1-positive T-cells were a prominent feature and UCHL-1-positive cells were increased in the epithelial compartment. Cells bearing surface immunoglobulins were widely distributed in all specimens, with IgA predominating. There was a relative increase in IgG-positive cells in the carcinomas. KP1-positive macrophages, S-100-positive dendritic cells, and HLA-DR-positive cells were oriented toward the lumenal surface in normal mucosa and hyperplastic polyps, suggesting a diffuse antigen presenting system. Macrophages and dendritic cells were increased and dispersed in the neoplasms. HLA-DR expression was increased in the neoplasms, mainly in the stromal cells. We conclude that there is an activated immune response in adenomas and carcinomas of the colon compared to normal mucosa. This is represented by expansion and reorganization of both the T- and B-cell compartments and the macrophage-cell systems.