Objective: To explore the immune escape mechanism by investigating the expression of B7.1, B7.2, ICAM-1 and MHCI, MHCII Ag in the cancer cells of cervical carcinoma.
Methods: The expressions of B7.1, B7.2 and ICAM-1, together with MHCI and IIAg were analyzed in tumor cells and interstitial cells of human cervical carcinoma with immunohistochemistry technique. The mRNA expressions of B7.1, B7.2 and ICAM-1 were observed by in situ hybridization.
Results: Out of the 42 fresh specimens analyzed with immunohistochemistry, the tumor cells expressed B7.1 Ag and ICAM-1 molecules in 22 and 27 specimens respectively, but not expressed B7.2; B7.1(+), B7.2(+) and ICAM-1(+) dendritic cells and lymphocytes were scattered more or less in the parenchyma and interstitum. Among the 37 cases studied for MHC Ag expression, the tumor cells expressed MHCI Ag and MHCIIAg in 32 and 4 cases respectively. No matter whether the tumor cells expressed MHCIIAg or not, MHCIIAg(+) dendritic cells were observed in the nests and the interstitial. When the same section staind for identifying, B7.1, B7.2 and MHCIIAg expressions was compared, by and large, the MHCIIAg(+) dendritic cells were always more numerous than B7.1, B7.1(+) or B7.2(+) ones. As for the 20 specimens inspected with in situ hybridization, the tumor cells in 11 and 12 cases expressed B7.1 mRNA and ICAM-1 mRNA respectively; Infiltrating dendritic cells and lymphocytes expressed B7.1 mRNA, B7.2 mRNA and ICAM-1 mRNA.
Conclusion: Tumor cells in most cervical carcinomas have the necessary elements for presenting antigen and evoking T lymphocytes activation, and there are a lot of dendritic cells infiltrated in the tumor tissues. These findings indicate that the mechanism for tumor escape may be attributed to the post-antigen presentation events.