Preferential expression of alpha B-crystallin in astrocytic elements of neuroectodermal tumors.

Recently the authors have identified a major component of Rosenthal fibers as alpha B-crystallin, a major lens protein. In the current study the authors investigated the expression of alpha B-crystallin in four cultured glioma cell lines and in 115 human neuroectodermal tumors. alpha B-crystallin was expressed differentially by those glioma cell lines, but not by neuroblastoma cell lines. Northern blot analysis revealed two distinct messages for alpha B-crystallin in C-6, whereas only a single message in U-373MG and G26-24. In human surgical specimens positive immunostaining was frequently observed in the following brain tumors: pilocytic astrocytoma of the juvenile type, anaplastic astrocytoma, glioblastoma multiforme, and subependymal giant cell astrocytoma. The astrocytic elements of mixed oligoastrocytomas, glioblastomas with sarcomatous components, and gangliogliomas were likewise strongly stained. In contrast, little immunoreactivity was observed in ependymal and choroid plexus tumors. Thus, alpha B-crystallin is mainly expressed by astrocytic tumors among neuroectodermal neoplasms, without regard to the presence of Rosenthal fibers.