Colonic lymphoid cell subsets and epithelial HLA-DR antigens in familial polyposis coli

Although there has been some evidence suggesting that immunological mechanisms are involved in the pathophysiology of familial polyposis coli (FPC), there has not been any report as to whether there is any abnormality of lymphoid cell subsets as background, whether polyps (adenomas) show different lymphoid cell subsets from the normal mucosa, or whether HLA-DR antigens are expressed on the epithelia of adenomas. Lymphoid cell subsets (CD5, CD4, CD8, IgA1, IgA2, IgM, IgD, IgG, and IgE positive cells) in the lamina propria, and HLA-DR antigens on the epithelia were studied in 7 patients with FPC. From each patient, 2 specimens were obtained from both the normal (non-polypoid) area and the polyp. Normal colonic mucosa, taken from 15 patients with conventional polyps or colorectal cancer, served as the normal control mucosa. Lymphoid cell subsets and HLA-DR antigens were identified by indirect immunoperoxidase staining using mouse anti-human monoclonal antibodies. In the normal area of FPC, lymphoid cell subsets were similar to those of normal control mucosa except for an increase in IgD positive (IgD+) cells. However, definite alterations were observed in the polyp. There were significant increases in the number of CD4+ and IgG+ cells, and in the sum of five classes of Ig+ cells compared to the normal area or normal control mucosa. HLA-DR antigens were not expressed in the normal control mucosa or in the normal areas, and only on the epithelia of the polyp in 5 out of 7 specimens (71%). These results clearly demonstrate that immunological reactions are involved in FPC polyps.