Histogenesis and cell lineage analysis of medulloblastomas

Although the histopathology, ultrastructural features, and cellular immunoreactivity for neuron-specific enolase and synaptophysin suggest that medulloblastomas are neuronal in character, the histogenesis of these tumors has not been firmly established due to conflicting observations surrounding the expression of intermediate filament proteins. In the present study the question of cell lineage in medulloblastomas was re-explored by examining tumors for the presence of neurofilament protein using a highly sensitive assay which employs a cocktail of monoclonal antibodies, as well as A2B5 antigen, and glial fibrillary acidic protein. With this assay, 12 of 14 tumors tested (86%) expressed high levels of both neurofilament protein and A2B5 antigen, whereas glial fibrillary acidic protein was either absent or expressed in very low percentages of the cells. The distributions of neurofilament and A2B5 antigens closely paralleled one another. These observations suggest that medulloblastomas have a common histogenesis from A2B5+ progenitor cells, and consistently manifest a trend toward neuronal rather than glial differentiation.