Antibodies against neuroactive amino acids and neuropeptides. II. Simultaneous immunoenzymatic double staining with labeled primary antibodies of the same species and a combination of the ABC method and the hapten-anti-hapten bridge (HAB) technique

Advances in quantitative immunohistochemistry and their contribution to breast cancer

Introduction: Automated image analysis provides an objective, quantitative, and reproducible method of measurement of biomarkers. Image quantification is particularly well suited for the analysis of tissue microarrays which has played a major pivotal role in the rapid assessment of molecular biomarkers. Data acquired from grinding up bulk tissue samples miss spatial information regarding cellular localization; therefore, methods that allow for spatial cell phenotyping at high resolution have proven to be valuable in many biomarker discovery assays. Here, we focus our attention on breast cancer as an example of a tumor type that has benefited from quantitative biomarker studies using tissue microarray format.Areas covered: The history of immunofluorescence and immunohistochemistry and the current status of these techniques, including multiplexing technologies (spectral and non-spectral) and image analysis software will be addressed. Finally, we will turn our attention to studies that have provided proof-of-principle evidence that have been impacted from the use of these techniques.Expert opinion: Assessment of prognostic and predictive biomarkers on tissue sections and TMA using Quantitative immunohistochemistry is an important advancement in the investigation of biologic markers. The challenges in standardization of quantitative technologies for accurate assessment are required for adoption into routine clinical practice.

Correlating habenular subnuclei in rat and mouse by using topographic, morphological, and cytochemical criteria

The mammalian habenulae consist of medial (MHb) and lateral (LHb) nuclear complexes. Especially the LHb has received much interest because it has been recognized as the potential center of an "anti-reward system." Subnuclear organization and connectivity of the LHb are well known. In contrast, criteria to classify habenular neurons into distinct groups with potentially different biological functions are missing, most likely as a result of the lack of appropriate marker proteins. Actually, a huge amount of data concerning the localization of more than 20,000 mouse protein genes is provided in the Allen Brain Atlas. Unfortunately, the immediate use of this information is prohibited by the fact that the subnuclear organization of the habenular complexes in mouse is not known so far. The present report, therefore, uses topographic, structural, and cytochemical information from the rat to recognize corresponding areas within the mouse habenulae. Taking advantage of the fact that the Klüver-Barrera technique allows simultaneous observation of neuronal cell bodies and myelinated fibers, we were able to correlate subnuclear areas in the mouse habenula to subnuclei, which had been rigorously identified by several criteria in the rat. Our data suggest that the topographic localization of habenular subnuclei is rather similar between mouse and rat and that they may be homologous in these two species. Consequently, our data may allow using the Allen Brain Atlas as a source of basal information, which should be helpful to select candidate molecular markers for functionally different neurons in the mouse and potentially in higher mammalian species.

Triple immunofluorescence labelling of parvalbumin, calbindin-D28k and calretinin in rat and monkey brain

This study presents novel techniques for the concomitant cytochemical detection of the calcium-binding proteins parvalbumin, calbindin-D28k and calretinin which are frequently used neuronal markers. For the triple immunofluorescence labelling of such antigens in rat and monkey brain--with emphasis on the cortex--we developed four different protocols which revealed obviously identical distribution patterns in consecutive sections. These methods included the simultaneous use of purified monoclonal antibodies directed against parvalbumin and calbindin--D28k--haptenized with biotin or digoxigenin--and subsequent visualization with fluorochromated hapten-recognizing immunoreagents. For the combined visualization of the calcium-binding proteins we applied the bright red fluorescent carbocyanine Cy3, blue fluorescent 7-amino-4-methylcoumarin-3-acetic acid (AMCA) and as green fluorophore either fluorescein or the newly introduced carbocyanine Cy2. The latter showed a higher fluorescence intensity and more resistance against photobleaching than fluorescein. In addition to clearly distinguished distribution patterns of the calcium-binding proteins, neurons co-expressing parvalbumin and calbindin-D28k in the parietal and piriform cortex of rat were demonstrated. The elaborated methods might stimulate the further detailed investigation of spatial and functional relationships between structures immunopositive for selected neuroanatomical markers.

Simultaneous detection of cytokine and immunophenotype at the single cell level by immunoenzymatic double staining

The goal of this study was to establish a generally applicable immunoenzymatic method for the simultaneous detection of cytokine and immunophenotype at the single cell level. Evaluating various cell preparations and staining protocols, we found that permeabilization by saponin (0.1%) is very efficient, in combination with glutaraldehyde (0.04%) as fixative. Among various staining procedures, sequential immunoperoxidase labelling of the cytokine by use of diaminobenzidine, and detection of the immunophenotype by use of 4-chloronaphthol proved most discriminative. The typical localization of the cytokine reaction product ('Golgi staining') within the cell, and the 'ring-like' staining for the immunophenotype on the cell surface, allowed precise identification of double-labelled cells. Primary monoclonal antibodies from the same species could be used without loss of sensitivity and specificity for either or both antigens. This method thus provides the opportunity to study morphology, cytokine and immunophenotype simultaneously at the single cell level with standard equipment. Its application for the analysis of tissue samples is in progress, and may allow us to incorporate the cytokine-type as a new parameter in histopathological diagnostics.

Association of N-ethylmaleimide-sensitive factor with synaptic vesicles

N-Ethylmaleimide-sensitive factor (NSF) mediates docking and/or fusion of transport vesicles in the multi-pathways of vesicular transport. NSF was highly expressed in brain and adrenal gland. Immunostaining of cerebellum with an anti-NSF monoclonal antibody showed that NSF is predominantly localized in the molecular layers and the glomeruli of the granule cell layers. This distribution coincided well with that of synaptophysin, a marker protein of synaptic vesicles. Purification and immunoprecipitation revealed that NSF is associated with brain synaptic vesicles. The present results suggest that NSF is associated with synaptic vesicles without Ca2+ influx.

Immunoelectron microscopic localization of the HPC-1 antigen in rat cerebellum

HPC-1 antigen is a neuron-specific 34 kDa protein, identical to p35A (syntaxin), and is thought to play important roles in docking or fusion of synaptic vesicles to presynaptic active zones. In the present study we analyze the distribution of HPC-1 antigen in rat cerebellum by a cryoimmunogold technique using an antibody against the fusion protein of beta-galactosidase and the HPC-1 antigen. HPC-1 antigen was detected at high density on the plasma membranes and synaptic vesicles of presynaptic boutons which formed synapses with dendrites of Purkinje cells, and on the plasma membranes of parallel fibres in the cerebellar molecular layer. In the granule cell layer, gold particles were also detected on the endoplasmic reticulum, nuclear membranes and the plasma membranes of granule cells. Presynaptic membranes and synaptic vesicles in glomeruli were also labelled by gold particles. To determine the topology of HPC-1 antigen on the membranes, the synaptosome fraction prepared from rat cerebellum was embedded in agarose, and processed for the pre-embedding protein A-gold technique. Intact synaptosomes were not labelled by gold particles. However, when fixed in hypotonic fixative to rupture plasma membranes, or when ruptured after fixation in normotonic fixative, the cytoplasmic surfaces of presynaptic membranes and synaptic vesicles were labelled by gold particles. These results suggest that most of the epitopes of HPC-1 antigen are located on the cytoplasmic surface of plasma membranes and synaptic vesicle membranes.

Practical suggestions for successful immunoenzyme double-staining experiments

Many methodologies exist to perform an immunoenzyme double staining. Hence, the practical problem arises as to which of these methods is optimal for one's own experimental design. A process of selection is described which is derived from our own practical experience. First, a general strategy is outlined for the handling of tissue sections to be used for multiple staining methods. Secondly, the selection of an appropriate immunoenzyme double-staining concept is made using a flow chart. Thereafter we give criteria for the definitive selection of an immunoenzyme double-staining protocol based on the characteristics of the tissue or cell type under study. Particular attention is given to the selection of appropriate detection systems, applying enzymes or gold particles, and good contrasting colour combinations. The problems of visualizing co-localization using immunoenzyme double staining are dealt with, and suggestions are made to adapt the method, if necessary, in order to optimize it.

Quantitative immunogold localization of Na, K-ATPase along rat nephron

Ultrastructural localization of Na, K-ATPase alpha-subunit along rat nephron segments was investigated quantitatively by immunogold electron microscopy on LR-White ultrathin sections using affinity-purified antibody against alpha-subunit of the enzyme. Ultrathin sections were incubated with the antibody at a saturation level and the number of gold particles bound per micron of the plasma membrane (particle density) of the tubular epithelial cells from the proximal tubule to the collecting duct was determined. In all the tubular epithelial cells, gold particles were located exclusively on the basolateral surface, and no significant binding of gold particles to the apical surface was observed. Distribution of gold particles on the basolateral membranes was quite heterogeneous; lateral membranes and infolded basal membranes were highly labeled, whereas the basal membranes which are in direct contact with the basal lamina were scarcely labeled. The average particle density on the basal surface was highest in the distal straight tubule cells (11.4 units), very high in the distal convoluted tubule cells (9.8 units), intermediate in the proximal tubule cells (3.3 units), in the connecting tubule cells (4.3 units), and in the principal cells of the collecting duct (5.6-3.8 units), low in the thin limb of Henle's loop (1.0 unit), and at the control level in the intercalated cells in the connecting and collecting duct. The relative number of gold particles/mm nephron segment and the relative number of gold particles in the various nephron segments were calculated using quantitative morphological data. The estimated distribution profile of the former was in good agreement with the Na, K-ATPase activity profile in rat nephron, which was determined biochemically with a microenzymatic method.