Detection of cell surface antigens in cryostat sections with immunogold-silver staining

Methods of Simultaneous Visualization of Cytoplasmic Enzyme Reactivity and Cell Surface Antigens (by Cytochemistry Combined with Immunocytochemistry) in Individual Hematopoietic and Lymphoid Cells

Enzyme cytochemistry alone, and more recently, immunocytohistochemistry have been satisfactorily used by hematologists and hematopathologists for the study, diagnosis and classification of human hematological and lymphoproliferative disorders. To enhance the potential of these techniques, the possibility of combining immunocytohistochemical techniques with enzyme cytohistochemistry with simultaneous visualization of both reaction products has been examined by some investigators. This approach has been applied to normal, reactive and neoplastic material using mainly cell suspensions and frozen sections, with the aim of improving cell identification in specimens containing different cell types, of determining the cytochemical profiles of well-defined lymphocyte subpopulations and of establishing the cell surface phe-notypes of cells that are positive for certain enzymes. In this paper, published reports on this subject are reviewed and compared with the experience of our study group.

Preparation, use, and enlargement of ultrasmall gold particles in immunoelectron microscopy

The introduction of ultrasmall (approximately 1-3 nm) colloidal gold markers in immunoelectron microscopy (IEM) in 1989 has considerably improved the sensitivity of this marker system. Ultrasmall gold markers have opened the field of pre-embedding labeling studies to gold markers without the need of harsh permeabilizing steps. They are recommended for the detection of scarce antigens in ultrathin cryosections which may otherwise escape immunodetection. However, reports concerning the preparation of ultrasmall gold colloids, their conjugation to proteins, and their use in high-resolution studies (without an additional enlargement step) are very limited. Also, the available enlargement techniques necessary for the use of this marker in conventional electron microscopy require detailed discussion to clarify the large number of contradictory observations. The present review summarizes and discusses the findings accumulated within the last 10 years on the application of ultrasmall gold markers in IEM with regard to their merits, limitations, detection sensitivity, and suitability for different labeling techniques. It should provide practical hints for the use of ultrasmall gold colloids and discusses problems arising with enlargement techniques such as silver enhancement and gold toning procedures.

Glucose transporters in rat peripheral nerve: paranodal expression of GLUT1 and GLUT3

Peripheral nerve depends on glucose oxidation to energize the repolarization of excitable axonal membranes following impulse conduction, hence requiring high-energy demands by the axon at the node of Ranvier. To enter the axon at this site, glucose must be transported from the endoneurial space across Schwann cell plasma membranes and the axolemma. Such transport is likely to be mediated by facilitative glucose transporters. Although immunohistochemical studies of peripheral nerves have detected high levels of the transporter GLUT1 in endoneurial capillaries and perineurium, localization of glucose transporters to Schwann cells or peripheral axons in vivo has not been documented. In this study, we demonstrate that the GLUT1 transporter is expressed in the plasma membrane and cytoplasm of myelinating Schwann cells around the nodes of Ranvier and in the Schmidt-Lanterman incisures, making them potential sites of transcellular glucose transport. No GLUT1 was detected in axonal membranes. GLUT3 mRNA was expressed only at low levels, but GLUT3 polypeptide was barely detected by immunocytochemistry or immunoblotting in peripheral nerve from young adult rats. However, in 13-month-old rats, GLUT3 polypeptide was present in myelinated fibers, endoneurial capillaries, and perineurium. In myelinated fibers, GLUT3 appeared to be preferentially expressed in the paranodal regions of Schwann cells and nodal axons, but was also present in the internodal aspects of these structures. The results of the present study suggest that both Schwann cell GLUT1 and axonal and Schwann cell GLUT3 are involved in the transport of glucose into the metabolically active regions of peripheral axons.

Dual staining of lymphocyte membrane antigens with colloidal gold and biotinylated horseradish peroxidase

Double immunoenzymatic labelling procedures for the localization of antigens on cells in tissue sections using horseradish peroxidase (HRP) and alkaline phosphatase have been described previously, but mainly for detecting antigens on different cells. With this type of staining when two antigens are present on the same cell, an optimal colour combination that shows a high contrast between the basic colour of each enzyme substrate product is difficult to achieve and the interpretation of their mixed colour intermediate is subjective. We present a method for the simultaneous demonstration of two antigens on the same cell. The method can be used to label either single cells in suspension, or cells in paraffin fixed tissue, using a combination of a particulate label, colloidal immunogold-silver, and an enzymatic label HRP-DAB. The method is easy to perform and utilises commercially available staining kits.

Detection of dengue virus antigens in cultured cells by using protein A-gold-silver staining (pAgs) method

A protein A-gold-silver (pAgs) staining was developed to detect dengue virus antigens in cultured cells. The method can be carried out in either newly-subcultured or monolayered cells. Dengue virus-inoculated C6/36 clone of Aedes albopictus cells and human endothelial cells appeared brown-yellowish color on the peripheral membrane of the infected cells. In many cases, the infected C6/36 cells appeared darker than that of the infected endothelial cells. The positive results from the inoculated C6/36 cells usually appeared as early as 2 days post-inoculation for types 1, 2, and 4 of dengue viruses and 3 days for the dengue 3 virus. The same batch of specimens detected by direct immunofluorescence antibody test (DFA) showed positive 4 days post-inoculation for the types 2, 3, and 4 of dengue viruses and 6 days for the dengue 1 virus. The result also showed that all pAgs-positive specimens were also DFA-positive, but not vice versa. It suggested that pAgs is not only sensitive but also specific for dengue virus detection from inoculated cultured cells.

Localization of cutaneous antigens by the immunogold-silver staining technique

Immunogold-silver staining (IGSS) was evaluated for the localization of cutaneous antigens in frozen and paraffin-embedded tissue, employing antibodies to a variety of intracellular, cell-surface and extracellular epitopes in an indirect immunogold reaction, followed by silver enhancement. The principal advantages of IGSS are the avoidance of toxic reagents and the production of a silver precipitate that is permanent, clearly visible and of sufficient contrast with the reaction products of alternative immunolocalizing techniques to be of value in double-labelling procedures. It seems to localize antigenic determinants well, but does not appear to be particularly sensitive, especially for the demonstration of antibodies to extracellular constituents. Limitations of IGSS include the propensity to non-specific staining, and the need to vary the duration of the development stage during silver enhancement.