No abstract

Intermediate-sized filament proteins (IFP) are tissue specific in that antibodies to keratin, vimentin, desmin, glial fibrillary acidic protein (GFAP) and the neurofilament proteins can distinguish between cells of epithelial and mesenchymal origin as well as of myogenic and neural origin respectively. Malignant cells retain their tissue-specific IFP, which makes it possible to use these antibodies in tumour diagnosis. Carcinomas are exclusively detected by antibodies to keratin. Monoclonal antibodies to keratin have allowed the differentiation between subgroups of epithelial tumours until now between adenocarcinomas and squamous cell carcinomas. Lymphomas, melanomas and several soft tissue tumours are distinctly recognized by antibodies to vimentin. On the other hand, rhabdomyosarcomas and leiomyosarcomas are positive for desmin, while astrocytomas give a strong reaction with GFAP antibodies. Thus, antibodies to IFP are useful tools for differential diagnosis in surgical pathology.

No abstract

This study reports on the use and evaluation of immunocytochemistry in diagnostic cytology by correlation with (immuno)histology. The cytologic material was collected during a period of 3 years. Sixty-four patients were selected and studied retrospectively. The reactivity of a number of polyclonal and monoclonal antibodies was investigated and applied to a diverse group of tumors. Marker expression on routine cytologic and histologic material was compared and the use of immunocytochemistry in diagnosis was evaluated. Immunocytochemistry proved to be an easy and valuable technique for the identification and classification of tumor cells, and there was a good concordance with immunohistology. A discrepancy in marker expression was found in 10% of the slides that were investigated. Immunocytochemistry led to a misdiagnosis in only four cases; however, in these cases cytology alone would not have led to the correct diagnosis. The causes for the discrepancies are discussed. It is estimated that immunocytochemistry contributed to the diagnosis of approximately 50% of the cases, supplying either additional or essential information. A wide variety of markers can be applied reliably on cytologic preparations. The use of panels of antibodies is mandatory. Cancer 65:2704-2711,1990.YTOLOGY is a diagnostic technique that is frequently C used because it is reliable and it generates a result within an hour. Frequently, however, a diagnosis of malignancy cannot be made and supported solely on cytomorphologic criteria, the classification of certain malignancies also can be difficult. Immunocytochemical staining procedures offer a method of increasing the accuracy of diagnosis in problematic cases.Several laboratories have reported the value of these techniques in diagnostic cytology. 1-6 In most of these studies a single antibody was used for the identification No published literature was found about a systematic correlation of cytology, immunocytochemistry, and histology and immunohistochemistry. The assessment of the value of immunocytochemistry in routine cytologic practice (except for selected cases) demands further research.The aim of this study was to compare the expression of different markers in cytologic material and to assess the value of markers as a routine diagnostic aid in the field of cytopathology.To achieve this aim, a number of polyclonal and monoclonal antibodies, available from commercial sources and routinely used for immunohistochemistry purposes, have been used to study routine cytologic material. A variety of tumors and reactive conditions were used in this study, including serous effusions ( i e . , pleural 2704

The leukocyte integrin LFA-1 (CD11a/CD18) plays a key role in many adhesive interactions involving cells of the immune system. Recently, it has been shown that LFA-1 is not only involved in cell adhesion, but that stimulation of LFA-1 can also contribute to cell activation. We now demonstrate that triggering of LFA-1 on T lymphocytes by monoclonal antibodies (mAb) against the LFA-1 alpha chain, but not against the LFA-1 beta chain, promotes cell adhesion. Induction of homotypic adhesion was only observed in T cells that had been pre-activated with anti-CD3 and not in resting peripheral blood T lymphocytes. The induced homotypic adhesion is mediated by LFA-itself, because it was inhibited by anti-LFA-1 beta mAb. This notion is supported by the temperature and divalent cation dependence which is characteristic of LFA-1-mediated adhesion. mAb against ICAM-1 (CD54) did not block LFA-1 alpha-induced adhesion. The sensitivity of LFA-1 alpha-induced adhesion to H7, which prevents the activation of protein kinase C and protein kinase A, and to cytochalasin B, which inhibits microfilament formation, suggests that the activation of the LFA-1 pathway through the LFA-1 alpha chain involves cell activation and requires an intact cytoskeleton.