EXPRESSION OF VS38 IN OSTEOBLASTS AND STROMA CELLS OF BONE-TUMORS

VS38 is a mouse monoclonal antibody which recognizes an intracytoplasm ic antigen of 64 kilodaltons present in normal and neoplastic cells. I t was reported to be of potential value in identifying myeloma or plas macytoma in bone marrow or other tissues. During diagnostic analysis o f bone marrow biopsies we noticed a consistent staining of osteoblasts with VS38. This led us to investigate the immunoreactivity in a range of bone lesions. 58 lesions were examined in the current study, inclu ding benign and malignant tumors as well as tumor like lesions and pro cesses with reactive bone formation. The Streptavidin-peroxidase compl ex technique was applied on paraffin embedded sections, with 3-amino-9 -ethyl-carbazole serving as chromogen. All osteoblasts of reactive ori gin and part of the osteoblasts of benign neoplasms showed positive im munostaining. The antibody stained stroma cells in 81.25% (13/16) of t he cases of benign osteogenic tumors and in 82.35% (14/17) of the oste osarcomas. Additionally, VS38 labelling was observed in bone tumors of fibrohistiogenic origin such as nonossifying fibroma and giant cell t umor, the histogenesis of which is still being debated. On the whole, it can be concluded that antibody VS38 lacks specificity as a plasma c ell marker. It shows, however, a striking affinity to osteoblasts and in part also to stroma cells of osteogenic and fibrohistiogenic bone t umors.