D2-40 immunohistochemistry--so far!

D2-40 is a commercially available monoclonal antibody directed against human podoplanin, a transmembrane mucoprotein that is expressed in lymphatic endothelial cells. Since its introduction, D2-40 immunoexpression has been described in a variety of lymphovascular neoplasms including lymphangioma, Kaposi sarcoma, and hemangioendothelioma, as well as nonvascular neoplasms such as epithelioid mesothelioma, seminoma, and hemangioblastoma. More recently, D2-40 immunoexpression has been reported in primary adrenal cortical tumors, schwannomas, and adnexal tumors of the skin. This brief review provides an update on the ever-expanding proposed applications of D2-40 immunohistochemistry in surgical pathology.

Histologic and histogenetic investigations of intracranial hemangioblastomas.

BACKGROUND: The aim of this study was to elucidate the histologic characteristics and the histogenesis of intracranial HBs. METHODS: Specimens from 40 patients with HBs were verified surgically and pathologically at the Huashan Hospital Department of Neurosurgery (Fudan University, Shanghai, China). All sections were immunohistochemically stained. In addition, fresh specimens were examined by electron microscopy in 3 cases and cells were cultured in 10. RESULTS: Hemangioblastomas were composed of endothelial cells, pericytes, and stromal cells. Vimentin was expressed in all 3 cell types of HB. CD34 was expressed in endothelial cells, and SMA was expressed in pericytes. Telomerase was expressed in stromal cells. Chromogranin A, CD68, and CD117 showed a negative reaction in HBs. Vascular endothelial growth factor showed a positive reaction in stromal cells, and Flt-1 showed a positive reaction in endothelial cells. There was no difference in immunohistochemical staining between specimens from cystic HBs and those from solid HBs. Three cell types had individual ultrastructural characteristics. Stromal cells represented a heterogeneity of abnormally differentiating mesenchymal cells in cell culture. CONCLUSIONS: Hemangioblastomas may originate from the mesenchyme. Stromal cells are the real tumor components of HBs although they represent a heterogeneity.

Inflammatory cell infiltrate in a responding metastatic nodule after vaccine-based immunotherapy.

A patient with von Hippel Lindau disease, bilateral symmetric renal cell carcinoma and pulmonary metastases treated with immunotherapy is the subject of this study. A left kidney and tumour mass were removed and the tumour cells used to make an autologous tumour/bacille Calmette-Guérin (BCG) vaccine as part of the treatment protocol. The patient's pulmonary nodules responded, but the remaining renal nodule subsequently grew. Samples of both tumours were obtained allowing for an internally controlled evaluation of the histological and immunohistologic differences between a responding and non-responding tumour nodule after therapy. The immunotherapy protocol is designed to promote a T cell response to autologous tumour. Cellular infiltrates were demonstrated in both responding and non-responding nodules compared with the pretreatment tumour specimen, but the responding nodule contained proportionately more T cells as well as markedly increased numbers of plasma cells and granulocytes. This suggested that several arms of the immune system may have been operative in the responding nodule.

Expression and distribution of vascular endothelial growth factor protein in human brain tumors.

Marked neovascularization is a hallmark of many neoplasms in the nervous system. Recent reports indicate that the endothelial mitogen vascular endothelial growth factor (VEGF) may play a critical role in the regulation of vascular endothelial proliferation in malignant gliomas. Using novel monoclonal antibodies to the VEGF polypeptide we have determined the expression and cellular distribution of VEGF protein in a representative series of 171 human central nervous system (CNS) tumors by immunohistochemistry and immunoblotting. In agreement with previous in situ hybridization data, 19 out of 20 glioblastomas (95%) showed immunoreactivity for VEGF, whereas both the percentage of immunoreactive tumors and the extent of immunoreactivity for VEGF were significantly lower in astrocytomas. Of the pilocytic astrocytomas (WHO grade I) 44% were immunoreactive for VEGF, but we observed several cases with pronounced vascular proliferates in the absence of VEGF. In ependymomas, meningiomas, hemangioblastomas, and primitive neuroectodermal tumors, there was no correlation between VEGF expression, vascular endothelial proliferation and the grade of malignancy. Oligodendrogliomas and the oligodendroglial component of mixed gliomas lacked immunoreactive VEGF, indicating that endothelial growth factors other than VEGF may regulate tumor angiogenesis in these neoplasms. Western blot analysis showed a predominant VEGF protein species of 23 kDa and confirmed the immunohistochemical data in all cases. Our findings demonstrate that VEGF is expressed in a wide spectrum of brain tumors in which it may induce neovascularization. However, other angiogenic factors also appear to contribute to the vascularization of CNS neoplasms.

High expression of the Glut1 glucose transporter in human brain hemangioblastoma endothelium.

The principal glucose transporter at the blood-brain barrier is Glut1, and GLUT1 expression is downregulated in high grade gliomas. In the present study, glucose transporter expression was studied in surgically resected hemangioblastoma tissue. Light microscopic immunochemistry indicated the high expression of the Glut1 glucose transporter isoform throughout the central vascular endothelium of this tissue. Glial fibrillary acidic protein (GFAP) was observed only at the tumor border, with no GFAP immunoreactivity in stromal cells, pericytes or endothelia in the central tumor regions. It is generally believed that more Glut1 is found in erythrocytes than any other cell, but quantitative electron microscopic immunogold analyses of Glut1-immunoreactive sites per micron of capillary membrane showed the Glut1 density in tumor endothelial membranes glucose transporter was 2-3-fold higher than in human red cells. In the same tissue samples, qualitative immunogold electron microscopy of human serum albumin indicated that this protein (MW 65,000) moved freely from the vascular space into pericapillary regions, confirming the leaky barrier characteristics of the hemangioblastoma. These studies show that Glut1 expression may be high in endothelia that are highly permeable and devoid of astroglial contacts. Thus, human cerebral hemangioblastomas may provide a novel system for studying the induction of Glut1 in the blood-brain barrier.

Immunohistochemical study of hemangioblastoma with special reference to its cytogenesis.

The cytogenesis of so-called hemangioblastoma arising in the central nervous system was investigated using the immunoreactivity to various proteins in cerebellar hemangioblastomas, extracerebellar hemangioblastomas, cerebral hemangiopericytomas, and hemangioendotheliomas, as well as a variety of meningiomas. The antisera used included vimentin, glial fibrillary acidic protein, epithelial membrane antigen, factor VIII-related antigen, and cytokeratin. Lipid-laden cells often encountered in partially degenerated meningiomas revealed almost identical reactivity patterns as the lipid-laden cells, i.e., so-called stroma cells, of hemangioblastomas. The results indicate that the so-called hemangioblastoma of the central nervous system is derived from arachnoid cells in meningotheliomatous meningiomas by way of cellular degeneration.