CHARACTERIZATION OF THE INFLAMMATORY CELL-POPULATIONS IN NORMAL COLONAND COLONIC CARCINOMAS

Little is known about the nature of the mucosa-associated immune syste m within the normal colon, or about the immune response to colon carci noma. In this study inflammatory cells (ICs) in 14 normal colons and 1 4 carcinomas were characterized. Overall inflammation, lymphocytes, pl asma cells, neutrophils, and eosinophils were graded in routine H & E sections. Frozen sections were stained by an immunoperoxidase techniqu e using antibodies to the T cell associated antigens CD2, CD7, CD4, CD 8, and T cell receptors alphabeta and gammadelta. B cells were identif ied with CD20, macrophages with CD68, and Class II antigen with anti-H LA DR. Each cell type was semiquantitatively graded in 10 high power f ields (HPFs) in the lumenal half (LH) or basal half (BH) of the normal mucosae, and in epithelium or stroma of the carcinomas. In normal col ons, ICs were more frequent in LH than in BH. Plasma cells, lymphocyte s and monocytes predominated. Subtyping of lymphocytes showed that CD4 + TCR alphabeta+ T lymphocytes were most numerous in the lamina propri a. Lymphocytes within the epithelium were CD8+ T cells. Around carcino mas the overall grade of ICs was 1+ in the majority of cases. Plasma c ells, CD4+ and CD8+ cells with the TCR alphabeta receptor, and macroph ages were most frequent. Lymphoid aggregates of both T and B cells wer e frequent. Conclusions: 1. Normal colon contains a diffuse lumenally oriented population of TCR alphabeta+ CD4+ T cells, plasma cells, macr ophages and class II antigen-expressing cells in the lamina propria. I ntraepithelial lymphocytes are of the T suppressor phenotype. CD4+ T c ells, macrophages and HLA-DR+ cells predominate in the response to col on carcinomas.