The epitope H contains an O-linked N-acetylglucosamine residue in a specific conformation and/or environment recognized by the monoclonal antibody H. It has previously been shown that the epitope H is present in several types of normal and pathological cells and in several polypeptides. In normal human brains the epitope H is present mostly to a minority of fibrous astrocytes, whereas it is greatly up-regulated in reactive astrocytes and is increased in well differentiated fibrillary astrocytomas compared to anaplastic astrocytomas and glioblastomas. In this study the expression of the epitope H was investigated in thirty cases of gemistocytic (WHO grade II), pilocytic (WHO grade I), and subependymal giant cell (WHO grade I) astrocytomas using the mAbH with the indirect immunoperoxidase method. The ten cases of gemistocytic astrocytomas revealed an overall high expression pattern. The ten cases of pilocytic astrocytomas revealed a biphasic pattern of epitope H expression. The dense tumor areas composed of elongated pilocytic cells revealed high expression of the epitope H. The loose cystic tumor areas composed of stellate cells revealed low expression of the epitope H. The ten cases of subependynal giant cell astrocytomas occurring in tuberous sclerosis revealed an overall high expression pattern. This study shows that there is high expression of the epitope H in gemistocytic, pilocytic and subependymal giant cell astrocytomas. Collectively considering, the present and our previous data, it appears that there is a spectrum of the expression levels of the epitope H ranging from the high expression in the reactive astrocytes and low grade astrocytomas to the low/null expression in the normal astrocytes and glioblastomas.

Related Articles