Association between HLA-expression and infiltration of immune cells in cervical carcinoma

To determine the degree of specificity of the cellular immune response in cervical carcinoma, that is known to be human papillomavirus-related, we investigated the exact relationship between in situ tumor-infiltrating immune cells and the monomorphic/allele-specific HLA expression on the tumor cells.

Attention was focussed on the type, location and number of in situ immunocompetent cells in malignant cervical tissue (N = 30). Immune cell distribution was quantitatively assessed by morphometry for stromal and tumor tissue separately. These results were related to the degree of expression of monomorphic- and allele-specific HLA I and II antigens on the cervical tumor cells.

In monomorphic HLA class I downregulated cervical tumors, a significant decrease in tumor-infiltrating CD8+ T cells was observed. However, allele-specific downregulation of respectively HLA-A2, HLA-A3, HLA-Bw4, and HLA-Bw6, did not correlate significantly with a decrease in tumor-infiltrating immune cells. For HLA class II-positive cervical tumors, HLA-DR expression significantly correlated with an increase in the presence of tumor-infiltrating CD3+/CD4+/CD8+ T cells, CD56+ natural killer cells and CD16+ macrophages. No significant correlations were found between alterations in HLA class I or II expression on the tumor cells and stromal infiltrating immune cells.

Our observations provide in situ immunomorphologic evidence that in cervical carcinoma, de novo expression of HLA class II antigens on the tumor cells resulted in an increase of tumor-infiltrating immune cells. In addition, the tumor-infiltrating CD8+ T lymphocytes correlated with monomorphic HLA class I expression on the tumor cells, which stresses the existence of a HLA-restricted immune response of T lymphocytes in cervical carcinoma. These findings might have implications for the biologic behavior of this disease and have to be taken into account in strategies concerning immunotherapy of cervical carcinoma.