EXPRESSION OF CLASS-III BETA-TUBULIN IN NORMAL AND NEOPLASTIC HUMAN TISSUES

The class III beta-tubulin isotype is widely used as a neuronal marker in normal and neoplastic tissues. This isotype was, however, also imm unodetected in certain tumours of non-neuronal origin such as squamous cell carcinoma. Using a newly described monoclonal antibody we compar ed the distribution of class III beta-tubulin in normal and neoplastic tissues, The TU-20 mouse monoclonal antibody was prepared against a c onserved synthetic peptide from the C-terminus of the human class III beta-tubulin isotype, and its specificity was confirmed by immunoblott ing, by competitive enzyme-linked immunosorbent assay and by immunoflu orescence microscopy on cultured cells. In different cell lines of var ious origins the antibody reacted only with neuroblastoma Neuro-2a cel ls and with embryonal carcinoma P19 cells stimulated to neuronal diffe rentiation by retinoic acid. Immunohistochemistry on formaldehyde-fixe d paraffin-embedded normal human tissues revealed the presence of the class III beta-tubulin isotype in cell bodies and processes of neurona l cells in the peripheral and central nervous systems. In other tissue s, this beta-tubulin isotype was not immunodetected. Class III beta-tu bulin was found in all cases of ganglioneuroblastoma, ganglioneuroma, medulloblastoma, neuroblastoma, sympathoblastoma and in one case of te ratoma. In contrast, no reactivity was detected in tumours of non-neur onal origin, including 32 cases of squamous cell carcinoma. The result s indicate a specific TU-20 epitope expression exclusively in neuronal tissues. The antibody could thus be a useful tool for the probing of class III beta-tubulin functions in neurons as well as for immunohisto chemical characterisation of tumours of neuronal origin.