Immunocytochemical demonstration of down regulation of HLA class-I molecule expression in human metastatic breast carcinoma.

Deficient expression of HLA class-I molecules observed in many cancers is suggested to influence both disease progression and potential efficacy of T cell-mediated immune therapy. Previous studies have attempted to correlate either primary breast cancer tumor grade with HLA class-I levels or the presence of HLA class-I-deficient cells in metastatic lesions with survival. In this study we evaluated the HLA class-I status of matched primary and secondary breast cancer lesions in order to ask the question: is metastasis of breast cancer associated with down-regulation of HLA class-I expression? Immunocytochemistry analysis shows a definitive correlation between diminished HLA class-I expression and dissemination of breast cancer to tumor-draining lymph nodes: both the total number of HLA class-I+ cells per sample and the levels of expression are dramatically decreased in secondary versus primary tumor lesions.