[Expression of major histocompatibility complex of advanced non-small cell lung cancer (NSCLC)]

Expression of major histocompatibility complex of lung cancer was examined to study the malignant potential of the tumor using immunochemical staining (anti-HLA class I monoclonal antibody; w6/32). Nuclear DNA contents and the labeling index of proliferating cell nuclear antigen (PCNA) were measured as well. Forty three advanced (p-stage IIIa) lung cancers resected by lobectomy (33 cases), pneumonectomy (9 cases), and segmentectomy (1 case) entered the study. Mediastinal lymph node dissection was performed in every case during the operation. Of the 43 cases, expression of HLA class I was positive in 17 and negative in 26. The patients with positive HLA expression showed significantly better prognosis than those with negative HLA expression in terms of 5 year survival (p < 0.01). The patients with aneuploid pattern and positive HLA class I expression had the best prognosis on the survival curve (p < 0.01). When the PCNA positive rate was high, the prognosis was poor. And the patients with negative PCNA and positive HLA class I expression had significantly better prognosis than the others (p < 0.01). These findings suggest that the expression of HLA class I on the tumor cells is an important prognostic factor in the patients with NSCLC.