Domenico Cocchia

Immunocytochemical localization of the brain-specific S-100 protein in the pituitary gland of adult rat.

SummaryThe brain-specific S-100 protein was localized at the electron microscopic level in the anterior and posterior pituitary gland of adult rat by indirect immunoperoxidase histology. The protein was found in the stellate cells of the pars distalis and tuberalis, in the marginal cells that line the hypophyseal cleft and in the glia-like cells, the pituicytes, of the neural lobe. The pituicytes, the stellate cells and the marginal cells have in common at least two properties: they all express a brain-specific marker and they are satellite cells to the secretory axons in the neural lobe and of the secretory cells in the adenohypophysis. These properties suggest that the S-100 cells in the pituitary gland are neuroectodermal in origin, possibly glial in nature.

Immunocytochemical localization of S-100 protein in the brain of adult rat

SummaryThe cellular and subcellular distribution of the nervous system-specific S-100 protein has been investigated in the brain of adult rat at the ultrastructural level by the pre-embedding unlabelled antibody PAP method. The protein is found in both fibrous and protoplasmic astrocytes and in the ependymal cells. The neurons, the oligodendrocytes as well as the microglial cells are lacking S-100. The labelled cells show a reaction product diffusely distributed in the cytoplasmic matrix and on specialized membranes, namely plasma membranes, outer mitochondrial membranes and membranes of the endoplasmic reticulum and Golgi apparatus. The astrocytic filaments and the axonemes of the ependymal cilia exhibit a strong immunoreactivity. The reaction product is also present in the nucleoplasm of the astrocytes and ependymal cells but it is absent from the nucleolus and nuclear envelope. This immunocytochemical data on tissue with satisfactory ultrastructural preservation, provides new information on the localization of the S-100 protein, and could contribute to the understanding of the biological role of the protein.

S-100 antigen in satellite cells of the adrenal medulla and the superior cervical ganglion of the rat

SummaryMeasurable amounts of the nervous-system specific S-100 protein were detected by microcomplement fixation assay both in the superior cervical ganglion and in the adrenal medulla of adult rats, though at a significantly higher concentration in the ganglion. By the unlabeled antibody PAP method, the antigen was localized at: he ultrastructural level in the Schwann cells and in the satellite cells of the ganglion, but not in neurons. Similarly, the protein was found in the Schwann cells of the adrenal medulla, but not in the chromaffin cells. Moreover, the S-100 immunolabeling allowed detection of a class of “satellite” cells closely enveloping the chromaffin cells. In the labeled cells of both organs the reaction product was diffusely distributed in the cytoplasmic matrix as well as in the nucleoplasm.The presence of the S-100 antigen in the satellite cells of the sympathetic ganglion and in “satellite” cells of the adrenal medulla suggests a possible homology for the two cell types, and one could hypothesize the presence in peptide hormone-secreting endocrine organs of glia-like cells exhibiting functional relationships with the secretory cells comparable to those of the glial cells with the neurons.

Immunochemical and immunocytochemical study of S-100 protein in rat adipocytes

S-100 is a protein originally believed to be unique to the nervous system. We report here on the presence of S-100 in rat adipocytes, using immunohistochemical and immunochemical methods. We demonstrate that the protein in adipose tissue is present at a concentration comparable to that measured in the nervous tissue and is immunologically identical to brain S-100, indicating that the protein can no longer be regarded as being specific to the nervous system.

The value of S-100 immunostaining as a diagnostic tool in human malignant melanomas

The brain proteins S-100 and neuron-specific enolase have been reported by separate groups to be present in human malignant melanomas. There is no systematic study comparing the occurrence of these proteins in the same tumour specimens. We have examined 33 primary malignant melanomas, including 5 which were amelanotic, and 25 metastatic melanomas using immunohistochemical methods with specific, non-cross-reacting antibodies to S-100 and NSE. We found S-100 immunoreactivity to be present in all cases but one, whereas NSE immnoreaction was very weak and patchy, and present in only 6 cases. S-100 immunoreactivity was not demonstrated in 40 control tumours, either primary or metastatic in skin, including basal- and squamous-cell carcinomas, spindle-cell sarcomas, lymphomas and Merkel cell tumours. All intradermal (n=4) and compound (n=1) naevi were positive for S-100, 2 blue naevi showing much less reaction. NSE immunoreactivity was detected in Merkel cell tumours (n=8), undifferentiated (n=2) and small cell (n=1) carcinomas, and all melanocytic naevi. It is suggested therefore that antibody to S-100 is the reagent of choice for demonstration of melanocytic tumours, and may be especially valuable in the diagnosis of amelanotic melanoma or metastatic tumours of doubtful origin where melanoma is suspected.

S-100 antigen labels neoplastic cells in liposarcoma and cartilaginous tumours

S-100 antigen, originally believed to be unique to the nervous system, has recently been found in cell types of non-neuroectodermal origin such as chondrocytes and adipocytes. These findings suggested the possibility of detecting the antigen in tumours derived from such cells. Using the PAP method and an anti-ox brain S-100, the antigen was found in the cells of human chondrosarcomas, chondroblastomas and liposarcomas. In contrast, fibrous histiocytomas and fibrosarcomas, tested to verify the cellular specificity of the S-100 immunoreaction, did not exhibit S-100-containing cell types. The present data indicate the usefulness of the S-100 antigen as a diagnostic and investigative tool in defined neoplasms of non-neuroectodermal origin, such as chondroid tumours and liposarcoma.

Neuronal and glial markers in tumours of neuroblastic origin

The presence and distribution of different neural markers in 30 neuroblastic tumours (neuroblastomas, ganglioneuroblastomas) and 6 non-neuroblastic tumours were investigated by immunocytochemistry. Neuron-specific enolase (NSE), S-100 protein, tyrosine hydroxylase, neurofilaments and glial fibrillary acidic protein (GFAP) were localized in 3 undifferentiated neuroblastic tumours (group A), 12 poorly differentiated tumours (group B) and 15 well differentiated neuroblastic tumours (group C). Non-neuroblastic tumours (3 lymphomas and 3 Ewing sarcomas) showed no immunoreactivity. Tyrosine hydroxylase and, in particular, NSE were found in mature ganglion cells and developing neuroblasts of poorly and well differentiated tumours (groups B and C). S-100 was localised in neuroblasts with slender cytoplasmic processes in the same groups. Neurofilaments were detected in ganglion cells and differentiated neuroblasts (groups B and C) while GFAP was localised in immature neuroblasts of undifferentiated and poorly differentiated tumours (groups A and B). Thus, there are differences in the neural proteins found in neuroblastic tumours and a wide panel of antibodies against neural markers may be a useful tool in the histological assessment of nervous system neoplasms.

Detection by S-100 immunolabelling of interdigitating reticulum cells in human thymomas

SummaryIn the light of recent findings concerning the presence of S-100 antigen in interdigitating reticulum cells (IRC’s) in the normal human thymus, we investigated the possible presence of these cells in human thymomas. By the unlabelled antibody PAP method, using an anti-S-100 antiserum, both by light and electron microscopy we were able to demonstrate immunolabelled IRC’s in the majority of spindle cell and in some round-oval cell thymomas. Keeping in mind the possible role of IRC’s in intrathymic T-cell differentiation, the present findings could be relevant in the better comprehension of this thymic neoplasm.

Immunocytochemistry of neuronal and glial markers in retinoblastoma

An immunocytochemical study of 30 retinoblastomas was carried out using antibodies to neuronal and glial markers. The tumours were found to react with antibodies to neuron-specific enolase (NSE), a marker for neuronal elements, and S-100 and glial fibrillary acidic protein (GFAP), both of which are proteins present in glia. Two distinct cell populations were found within the tumour: the first, composed of anaplastic tumour cells at various stages of differentiation, showed both NSE and S-100 immunoreactivity; the second cell type, which immunostained for S-100 and GFAP, resembled mature glial cells. The results of this study indicate that the retinoblastoma may arise from a pluripotential primitive cell partially retaining neuronal and glial characteristics.

S-100 protein in “follicular dendritic” cells of rat lymphoid organs

SummaryThe presence as well as the cellular and subcellular distribution of S-100 protein were investigated in lymphoid organs of the adult rat by quantitative microcomplement fixation assay and by the immunocytochemical PAP method at the ultrastructural level. The protein appeared to be confined to the “follicular dendritic” cells both in the lymph node and the spleen, which are known to be exclusively associated with B lymphocytes in secondary follicles. The present data show an additional location for S-100 outside the nervous system. The protein may also be a useful tool to provide information on the origin and function of “follicular dendritic” cells, which are still poorly understood.