LYMPHOCYTE SUBSET INFILTRATION PATTERNS AND HLA-ANTIGEN STATUS IN COLORECTAL CARCINOMAS AND ADENOMAS

Fifty eight large bowel adenocarcinomas and 20 adenomas were studied i mmunohistochemically, using fresh frozen tissue sections, with regard to lymphocyte subpopulations (CD3, CD4, CD8, CD19, and CD20) in the in flammatory infiltrate and to expression of human leucocyte antigens (H LA-ABC, HLA-AZ, and HLA-DR). The findings were related to differentiat ion and Dukes's stage of carcinoma. The inflammatory infiltrate was fo und to have a phenotype that remained constant irrespective of the int ensity of the inflammation. CD4 and CD3 positive cells predominated wi th fewer CD8 positive cells and a scanty diffuse CD19/20 positive cell population. CD19/20 follicular aggregates were common at the advancin g margin of the carcinomas. There was no significant association with Dukes's stage, differentiation or HLA status. HLA changes (ABC loss, A 2 loss, and DR gain) were associated with differentiation, being more common and more extensive in poorly differentiated carcinomas. HLA-A2 loss was also associated with stage of progression of carcinoma. Infla mmation associated with adenomas was found to have a similar phenotype to that associated with carcinomas. HLA changes in adenomas were unco mmon, being seen in only one of our 20 cases.