[S-100 protein positivity in osteogenic tumours and tumour-like bone forming lesions]

Various osteogenic tumours and bone producing tumour-like lesions of bone were examined for S-100 protein using the immunostaining methods. The positive reaction for S-100 protein of some bone cells was detected not only in osteoblastic osteosarcomas and osteoblastomas, but also in osteoplastic reactive lesions, fibrous dysplasia, Paget's disease and in the tissue of the bony callus. The positive reaction for osteocalcin in these cells showed, that they may be of osteoblastic and osteocytic lineage. The S-100 protein positive bone cells have to be differentiated from chondrocytes persisting in new-formed bone trabecullae. On the one hand S-100 protein positive osteocytes and osteoblasts may represent transient form of osteocytes histogenetically related to chondrocytes, but we were not able to prove such suggestion. Therefore, S-100 protein positivity can be caused by polyclonal character of the used antibody, that is a mixture of three antibodies, S-100 A1, A6 and anti B2. The specificity of these three components differs depending on the histogenesis of cells and their functional status. Such explanation is supported by the results of our study, because we also observed intense positivity of bone cells in the reaction with monoclonal antibody against S-100A6. In contrast, no staining of bone cells was detected with monoclonal antibodies against S-100 A1 and B2.