[Intermediate filament proteins as markers in tumor diagnosis].

Classification of tumors is based on histogenesis and on determination of malignancy. In well differentiated neoplasias the tumor tissue reveals a similar morphological pattern similar to that of the normal tissue from which they have originated. In contrast less differentiated neoplasias do not show such similarities to normal tissue in conventional stains and special procedures such as electron microscopy or immunohistology have to be performed in order to detect cell specific products. In many undifferentiated tumors this is not possible because loss of differentiation and organisation in tumor cells do not allow the production of cell specific substances. A new possibility for determining the histogenesis of tumors is the use of antibodies which are specific for one type of intermediate filaments. Intermediate filaments are structures, which together with microtubules and microfilaments form the cytoskeleton. Intermediate filaments are composed of different polypeptides, which show a cell type specificity. Keratins are the intermediate filaments characteristically found in keratinizing and nonkeratinizing epithelia. Desmin is the specific intermediate filament type of sarcomeric, visceral and some type of vascular smooth muscle tissue. Vimentin filaments are characteristic of endothelial cells, fibroblasts, macrophages, chondrocytes and most but not all lymphatic cells and the only intermediate filament type present in these cells. Neurofilaments are composed of three different polypeptides, which form the so called neurofilament triplet and are characteristically found in central and peripheral neurons. Glial fibrillary acidic protein (GFAP) forms the intermediate filament system of normal and reactive astrocytes and also some ependymal cells contain GFAP. Thus cells and tissues can be divided into five different types by the use of appropriate polyclonal or monoclonal antibodies. In the current study we were interested to determine with a large number of specimens, whether primary tumors or metastases continue to express the intermediate type characteristic of the normal tissue. The following results demonstrate, there is abundant evidence that intermediate filaments can be used as cell type specific markers both for normal tissue and for tumors. 1. To exclude wrong negative results by intermediate filament typing, a reliable detection of intermediate filaments should be performed on cryostat sections or on material, which has been recently ethanol fixed and paraffin embedded. With many antibodies fixation of the tissue in formalin results in a decrease of reactivity.(ABSTRACT TRUNCATED AT 400 WORDS)