The number of regulatory Foxp3+ T-cells in different stages of malignant transformation of large intestinal polyps.

Purpose: The aim of this study was to determine the relationship between the number of regulatory T-cells (Tregs) at various stages of malignant transformation of large intestinal polyps.

Material/methods: The study included tissue specimens from individuals subjected to complete colonoscopy with polypectomy and from patients who underwent surgical resection of colorectal tumors. This group included 27 individuals, among them 10 women (37%). Median age of the patients was 64 years (range 37-82 years). Surgical specimens included hyperplastic polyps (n=4), adenomatous polyps with low- (n=5) and high-grade dysplasia (n=8) and invasive colorectal cancers (n=10). Tregs were identified immunohistochemically.

Results: Mean number of Foxp3+ T-cells per 10 high-power fields (HPFs) increased in line with malignant transformation, from 12.5 for hyperplastic polyps, 29.4 and 36.5 for adenomatous polyps with low- and high-grade dysplasia, respectively, to 56.3 for invasive colorectal cancers (p=0.00). An increase in the mean number of CD4+ T-cells was also observed, from 45.75, 57.8, 84.125, to 110.6 per 10 HPFs, respectively, however this change did not prove to be statistically significant (p=0.13). Mean Foxp3+/CD4+ T-cell ratio increased in line with malignant transformation (from 0.27, 0.3, 0.43, to 0.5), although a statistically significant change of this parameter was only observed in the case of invasive colorectal cancers (p=0.01).

Conclusions: An increase in the number of Tregs in the lymphocytic infiltrate of large intestinal polyps is interestingly already observed at early stages of carcinogenesis. Proportions of various T-cell subpopulations in the infiltrate vary considerably depending on the degree of dysplasia, especially in the case of invasive colorectal cancer.