Biological characterization of human bone tumors. VIII. Expression of HLA-DR antigens in bone tumors and tumor-like lesions.

A total of 45 cases of bone tumors and tumor-like lesions were studied in order to determine the expression of an HLA-DR antigen by the monoclonal antibody 910-D-7, and its possible correlation with histology, using the indirect immunoperoxidase method on frozen sections. The pattern of antigen expression was nearly constant for the individual cell types, though varying in intensity, and did not depend on the biological behavior of the respective lesions. No clear correlation could be established between antigen expression and cell maturation. Although the biological significance of antigen expression in these tumors is not yet understood, it is clear that here, too, the mere presence of an HLA-DR antigen cannot be interpreted as a sign of malignant transformation.