Immunohistochemistry of central nervous system tumors. Its contributions to neurosurgical diagnosis

Applications of monoclonal antibodies in the diagnosis and treatment of primary brain tumors

The development of monoclonal antibodies has resulted in marked expansion in understanding the central nervous system (CNS). This has been especially true in the study of human neuroectodermal tumors where monoclonal antibodies have been used as physiological probes to define and characterize human neuroectodermal tumor-associated antigens. Utilizing monoclonal antibodies, neuroectodermal tumor-associated antigens have been described in four broad categories; biochemically defined markers, shared nervous system-lymphoid cell markers, shared neuroectodermal-oncofetal markers, and putative restricted tumor markers. Preliminary data have demonstrated the ability to localize animal and human tumors in vitro, ex vivo, and in vivo. Early application of monoclonal antibody technology to neuroimmunology and neuro-oncology has resulted in a new awareness of the complex relationships that exist within the CNS. Their specificity and reproducibility may provide the means to qualitatively and quantitatively define the phenotypic heterogeneity of human neuroectodermal tumors. Potentially, monoclonal antibodies, alone or as carriers of radionuclides, drugs, or toxins, may allow successful diagnosis and treatment of human neuroectodermal tumors.

Differentiation markers (S-100, GFAP, NSE and D2) in fetal rat brain cells during malignant transformation in cell culture

Malignant cell lines obtained by ethylnitrosourea (EtNU)-induced transformation of fetal rat brain cells in culture express protein markers of different types of neural cells. These are the nervous system-characteristic S-100 protein; glial fibrillary acidic protein (GFAP); neuron-specific-enolase (NSE), and the D2-cell adhesion molecule. S-100 protein was absent in fetal brain cells in culture, but gradually appeared in the later stages of malignant transformation and further increased at onset of rapid growth of atypical cells (stage IV). GFAP and D2 were weakly expressed in primary fetal brain cells and did not change throughout malignant transformation. NSE was present in both normal and carcinogen-treated fetal brain cells, and increased at later stages of malignant transformation. From stage III (40-100 days) some cultures were strongly positive and some negative, and the same was seen in the resulting tumorigenic cells about 100 days later. In conclusion the stepwise process of malignant transformation of brain cells in culture ended with a stable phenotype of cells capable of expressing varying types of differentiation markers. The presence of these markers in rat brain cells undergoing malignant transformation may indicate that EtNU given at 18th days of gestation is acting on multipotent neuroectodermal cells.

Immunocytochemistry of folliculo-stellate cells of normal and neoplastic human pituitary gland

Five normal human pituitaries and 20 pituitary neoplasms were investigated by immunocytochemical methods. Glial fibrillary acidic protein and S100 have been shown in the anterior lobe of the pituitary. Both these markers were present in the folliculo-stellate cell. Evidence is presented for the presence of a transitional folliculo-stellate cell which is immunoreactive for S100. The role of the folliculo-stellate cell is discussed.

Immunohistochemical recognition of human nerve sheath tumors by anti-Leu 7 (HNK-1) monoclonal antibody

Using relatively high dilutions of anti-Leu 7 monoclonal antibody and a four-step peroxidase-antiperoxidase (PAP) reaction in paraffin-embedded tissues, we tested the affinity of this antibody to the cells of 47 human nerve sheath tumors and 22 other tumors in which the differential diagnosis with nerve sheath neoplasms is known to arise. Of all the nerve sheath tumors studied 68%, including 80% of the schwannomas, contained anti-Leu 7-positive cells. All 22 non-schwannian neoplasms were entirely negative. Specimens of eight experimental malignant rat schwannomas were also negative for anti-Leu 7 antibody. Our findings suggest that anti-Leu 7 monoclonal antibody is a promising marker that may facilitate the differential diagnosis between human Schwann cell and non-Schwann cell neoplasms.

Immunocytochemistry of cerebellar astrocytomas: with a special note on Rosenthal fibres

Two astrocytic immunocytochemical markers, glial fibrillary acidic protein (GFAP) and glutamine synthetase (GS), were demonstrated in cerebellar astrocytomas. The staining pattern for both antigens was similar, but GFAP demonstrated astrocytic processes better, while GS staining was stronger in poorly fibrillated cells. The various astrocytic forms, bipolar, stellate, bi- and multi-nucleate cells, displayed different immunostaining. Rosenthal fibres also showed a varying pattern of reaction: larger fibres were entirely negative or had a narrow peripheral ring of dense reaction product, but occasional smaller fibres were positive. The varying proportion of filamentous and amorphous material within Rosenthal fibres could be responsible for this finding. The pale granular bodies possessed a GFAP-positive limiting membrane and GS-positive contents, suggestive of their astrocytic origin. Immunohistochemistry of GFAP and GS has contributed to the knowledge of cellular differentiation and secondary changes in cerebellar astrocytomas.

Expression of vimentin, glial filament, and neurofilament proteins in primitive childhood brain tumors. A comparative immunoblot and immunoperoxidase study

Two methods of determining intermediate filament protein (IFP) expression by primitive brain tumors of childhood were compared using a panel of monoclonal antibodies to three classes of IFP. In addition to a controlled immunohistochemical study, a group of these tumors was subjected to direct immunologic assay of tumor-extracted IFP using the western blot method. Western blots of IFP extracted from ten prospectively microdissected brain tumors revealed no NF200 or NF150 in any tumor. Traces of NF68, VFP, and GFP were detected by this sensitive method in four, three, and six cases, respectively. Immunohistochemistry, using the same monoclonal antibodies on adjacent tumor sections, yielded results significantly different from the immunoblotting method: no NF proteins or VFP were detected, but immunoreactive GFP could be seen in a small percentage of cells in each case. A retrospective study of 46 primitive tumors, using only immunohistochemistry, showed GFP to be the most common source of immunopositivity (38 cases), followed by VFP (15 cases), but most positive cells were judged to be reactive astrocytes. NF protein was not detected except in three cases in which extremely rare cells had morphological features of neurons. Cells which were clearly malignant, and which constituted the majority of cells in a microscopic field, were devoid of any IFP immunoreactivity. The advantages and limitations of each method of IFP detection in this group of primitive tumors and the implications of the apparent paucity of mature neural IFP in these tumors are discussed.