Objectives: In this study, we investigated MHC-class I expression on both prostate cancer and normal prostate and compared those data with the number of CD8+ lymphocyte. Secondary, we investigated effect of IFN-gamma to the MHC-class I expression on prostate carcinoma.
Materials and methods: Twenty cryo-preserved benign prostate samples (Seven normal prostates and five benign prostatic hypertrophy samples.) and fifteen prostate carcinoma samples were used for immunohistochemistry of CD8 and MHC-class I. Eleven fresh single cell suspensions of prostate carcinoma were used for IFN-gamma study. After 24 hours IFN-gamma stimulation, MHC-I expression was measured by FACs analysis.
Results: Interestingly, significant correlation was observed between MHC-class I expression and the CD8+ lymphocyte infiltrate (r = 0.705, P < 0.0001). After 24 hrs IFN-gamma stimulation, MHC-class I expression was up-regulated in all samples (p < 0.05).
Conclusion: Reduced expression of MHC-class I was thought as one of the factor which is related to the reduced degree of TILs (tumor infiltratig lymphocytes) in prostate cancer. IFN-gamma which is secreted mainly from CTL (cytotoxic T lymphocyte) might increase the degree of TIL through up-regulated MHC-class I.