HLA class I antigens expression in renal cell carcinoma: histopathological and clinical correlation.

Immunohistochemical analysis of HLA class I antigens expression in 26 renal cell carcinomas (RCCs)--18 clear cell, 6 granular and 2 chromophobe--was performed with indirect immunoperoxidase method. Results were correlated with extent and immunophenotype of tumor infiltrating mononuclear cells, histopathological (histology, cytology, grade, presence of necrosis) and clinical (tumor diameter, TNM classification) characteristics of RCC. 4 (15%) RCCs showed reduced HLA class I presence and this was associated with greater tumor diameter and more frequent T3, T4 and M1 stage. All tumors with altered HLA class I antigens expression were grade 2 or 3 and strong correlation with presence of necrosis (p=0.006) was noticed, while mononuclear cell infiltrates (especially CD8+ T lymphocytes) were less extensive compared to tumors with normal HLA class I level. Our results suggest more aggressive clinical behavior of RCCs with reduced HLA class I antigens expression, probably due to impaired cellular antitumor immune response.