LOCALIZATION OF THE NEURONAL CLASS-III BETA-TUBULIN ISOTYPE IN FOCI OF EARLY NEURITOGENESIS SUPPORTS DIVERGENT NEUROBLASTIC DIFFERENTIATIONPOTENTIAL IN WILMS-TUMORS

Wilms' tumors are embryonic neoplasms that have been proposed to origi nate from the metanephric blastema and are capable of divergent epithe lial and mesenchymal differentiation. Neuroepithelial differentiation in these tumors remains controversial. The aim of this study was to ex amine the phenotypic profile of certain neuronal and glial antigenic d eterminants in a series of 21 Wilms' tumors. Immunohistochemical studi es were performed by using monoclonal antibodies against the neuronal class III beta-tubulin isotype (beta III), the phosphorylated and phos phorylation-independent epitopes of neurofilament protein, and synapto physin; antisera to gamma-enolase (neuron-specific enolase), glial fib rillary acidic protein, and S100 protein were also used. Foci of neopl astic cells with neurite-like processes that exhibited intense beta II I staining were demonstrated in blastemalike areas of three of 21 tumo rs. In one case, Homer Wright rosettes (stained for beta III) were ide ntified. Areas of abortive neuritic development were also labeled with antibodies to gamma-enolase. No reactivity was obtained in these foci for phosphorylated and phosphorylation-independent epitopes of neurof ilament protein, synaptophysin, glial fibrillary acidic protein, and S 100 protein. The remainder of the tumors (18 of 21) were negative with the panel of neural markers. Our results indicate that divergent neur oblastic differentiation, evidenced as early neoplastic neuritogenesis , may be present in the blastematous component of Wilms' tumor subsets .