Triple immunofluorolabeling with two rabbit polyclonal antibodies and a mouse monoclonal antibody allowing three-dimensional analysis of cotton wool plaques in Alzheimer disease

11C-PiB PET can underestimate brain amyloid-β burden when cotton wool plaques are numerous

Individuals with familial Alzheimer's disease due to PSEN1 mutations develop high cortical fibrillar amyloid-β load but often have lower cortical 11C-Pittsburgh compound B (PiB) retention than Individuals with sporadic Alzheimer's disease. We hypothesized this is influenced by limited interactions of Pittsburgh compound B with cotton wool plaques, an amyloid-β plaque type common in familial Alzheimer's disease but rare in sporadic Alzheimer's disease. Histological sections of frontal and temporal cortex, caudate nucleus and cerebellum were obtained from 14 cases with sporadic Alzheimer's disease, 12 cases with familial Alzheimer's disease due to PSEN1 mutations, two relatives of a PSEN1 mutation carrier but without genotype information and three non-Alzheimer's disease cases. Sections were processed immunohistochemically using amyloid-β-targeting antibodies and the fluorescent amyloid stains cyano-PiB and X-34. Plaque load was quantified by percentage area analysis. Frozen homogenates from the same brain regions from five sporadic Alzheimer's disease and three familial Alzheimer's disease cases were analysed for 3H-PiB in vitro binding and concentrations of amyloid-β1-40 and amyloid-β1-42. Nine sporadic Alzheimer's disease, three familial Alzheimer's disease and three non-Alzheimer's disease participants had 11C-PiB PET with standardized uptake value ratios calculated using the cerebellum as the reference region. Cotton wool plaques were present in the neocortex of all familial Alzheimer's disease cases and one sporadic Alzheimer's disease case, in the caudate nucleus from four familial Alzheimer's disease cases, but not in the cerebellum. Cotton wool plaques immunolabelled robustly with 4G8 and amyloid-β42 antibodies but weakly with amyloid-β40 and amyloid-βN3pE antibodies and had only background cyano-PiB fluorescence despite labelling with X-34. Relative to amyloid-β plaque load, cyano-Pittsburgh compound B plaque load was similar in sporadic Alzheimer's disease while in familial Alzheimer's disease it was lower in the neocortex and the caudate nucleus. In both regions, insoluble amyloid-β1-42 and amyloid-β1-40 concentrations were similar in familial Alzheimer's disease and sporadic Alzheimer's disease groups, while 3H-PiB binding was lower in the familial Alzheimer's disease than the sporadic Alzheimer's disease group. Higher amyloid-β1-42 concentration associated with higher 3H-PiB binding in sporadic Alzheimer's disease but not familial Alzheimer's disease. 11C-PiB retention correlated with region-matched post-mortem amyloid-β plaque load; however, familial Alzheimer's disease cases with abundant cotton wool plaques had lower 11C-PiB retention than sporadic Alzheimer's disease cases with similar amyloid-β plaque loads. PiB has limited ability to detect amyloid-β aggregates in cotton wool plaques and may underestimate total amyloid-β plaque burden in brain regions with abundant cotton wool plaques.

Peptide Antibodies in Clinical Laboratory Diagnostics

Peptide antibodies, with their high specificities and affinities, are invaluable reagents for peptide and protein recognition in biological specimens. Depending on the application and the assay, in which the peptide antibody is to used, several factors influence successful antibody production, including peptide selection and antibody screening. Peptide antibodies have been used in clinical laboratory diagnostics with great success for decades, primarily because they can be produced to multiple targets, recognizing native wildtype proteins, denatured proteins, and newly generated epitopes. Especially mutation-specific peptide antibodies have become important as diagnostic tools in the detection of various cancers. In addition to their use as diagnostic tools in malignant and premalignant conditions, peptide antibodies are applied in all other areas of clinical laboratory diagnostics, including endocrinology, hematology, neurodegenerative diseases, cardiovascular diseases, infectious diseases, and amyloidoses.

Registration of whole immunohistochemical slide images: an efficient way to characterize biomarker colocalization

BACKGROUND AND OBJECTIVE

Extracting accurate information from complex biological processes involved in diseases, such as cancers, requires the simultaneous targeting of multiple proteins and locating their respective expression in tissue samples. This information can be collected by imaging and registering adjacent sections from the same tissue sample and stained by immunohistochemistry (IHC). Registration accuracy should be on the scale of a few cells to enable protein colocalization to be assessed.

METHODS

We propose a simple and efficient method based on the open-source elastix framework to register virtual slides of adjacent sections from the same tissue sample. We characterize registration accuracies for different types of tissue and IHC staining.

RESULTS

Our results indicate that this technique is suitable for the evaluation of the colocalization of biomarkers on the scale of a few cells. We also show that using this technique in conjunction with a sequential IHC labeling and erasing technique offers improved registration accuracies.

DISCUSSION

Brightfield IHC enables to address the problem of large series of tissue samples, which are usually required in clinical research. However, this approach, which is simple at the tissue processing level, requires challenging image analysis processes, such as accurate registration, to view and extract the protein colocalization information.

CONCLUSIONS

The method proposed in this work enables accurate registration (on the scale of a few cells) of virtual slides of adjacent tissue sections on which the expression of different proteins is evidenced by standard IHC. Furthermore, combining our method with a sequential labeling and erasing technique enables cell-scale colocalization.

Local delivery of recombinant human bone morphogenetic protein-2 increases axonal regeneration and the expression of tau protein after facial nerve injury

This study explored the function and possible mechanism of bone morphogenetic protein-2 (BMP-2) in the healing of injured peripheral nerves in vivo. Rabbit facial nerves were injured by clamping and then treated with recombinant human BMP-2 (rhBMP-2) or phosphate-buffered saline (control) by injecting once during surgery and twice a day post-injury for 7 days. Facial nerve fragments within 5 mm of the clamping point were examined at different times post-surgery. Axon structures visualized by Bielschowsky staining were similar in experimental and control nerves 2 and 6 weeks post-injury. At 4 weeks post-injury, cross-section images of facial nerves showed that axons treated with rhBMP-2 were denser and thicker, and levels of tau protein were increased. It is concluded from these data that rhBMP-2 may affect injured facial nerve regeneration by inducing more neurons to return to embryonic patterns of tau gene expression.

Narrow-banding images and structures of microvessels of colonic lesions

BACKGROUND

Magnifying colonoscopy with NBI has been shown to be useful for the differential diagnosis of tumors. However, the relationship between findings on NBI magnification and the microvessel architecture of colorectal lesions remains to be clarified.

AIMS

The aim of this study was to clarify the correlation between NBI findings and the microvascular architecture of colorectal lesions according to the depth of microvessels from the mucosal surface.

METHODS

A total of 22 colorectal lesions (11 tubular adenomas and 11 hyperplasia) obtained from 22 patients were studied. These lesions were analyzed microscopically on tissue specimens immunostained with CD34. Three-dimensional images were reconstructed from serial sections of tubular adenomas, hyperplasia, and normal mucosa.

RESULTS

Three-dimensional reconstructed images of tubular adenoma and normal mucosa to a depth of less than 150 μm from the mucosal surface showed similar structures to images obtained by NBI magnification. Microvessel diameter was significantly larger in tubular adenoma than in normal mucosa (P = 0.002) and hyperplasia (P = 0.034), and microvessel area was significantly larger in tubular adenoma than in normal mucosa (P < 0.001) and hyperplasia (P < 0.001) only in the superficial mucosal layer (to a depth of less than 150 μm).

CONCLUSIONS

TA was characterized by thicker microvessels and higher volume of microvessels than NM and HP. Compared with white light, NBI can more accurately depict the characteristics of microvessels because it uses light with short wavelengths, thereby contributing to high diagnostic capability.

Concomitant detection of beta-amyloid peptides with N-terminal truncation and different C-terminal endings in cortical plaques from cases with Alzheimer's disease, senile monkeys and triple transgenic mice

The disturbed metabolism of beta-amyloid peptides generated from amyloid precursor protein is widely considered as a main factor during the pathogenesis of Alzheimer's disease. A neuropathological hallmark in the brains from cases with Alzheimer's disease are senile plaques mainly composed of hardly soluble beta-amyloid peptides comprising up to 43 amino acids. Age-dependent cortical beta-amyloidosis was also shown in several transgenic mice and old individuals from various mammalian species, e.g., non-human primates. Beta-amyloid(1-42) is believed to be the main component in the core of senile plaques, whereas less hydrophobic beta-amyloid(1-40) predominantly occurs in the outer rim of plaques. Amino-terminally truncated pyroglutamyl-beta-amyloid(pE3-x) was recently found to be a beta-amyloid species of high relevance to the progression of the disease. While a few biochemical studies provided data on the co-occurrence of several beta-amyloid forms, their concomitant histochemical detection is still lacking. Here, we present a novel triple immunofluorescence labelling of amino- and differently carboxy-terminally truncated beta-amyloid peptides in cortical plaques from a case with Alzheimer's disease, senile macaques and baboons, and triple transgenic mice with age-dependent beta-amyloidosis and tau hyperphosphorylation. Additionally, beta-amyloid(pE3-x) and total beta-amyloid were concomitantly detected with beta-amyloid peptides ending with amino acid 40 or 42, respectively. Simultaneous staining of several beta-amyloid species reveals for instance vascular amyloid containing beta-amyloid(pE3-x) in Alzheimer's disease and monkeys, and may contribute to the further elucidation of beta-amyloidosis in neurodegenerative disorders and animal models.

Fluorochromes: properties and characteristics

Immunofluorescence microscopy provides a sensitive means by which antigens can be localized within tissues or individual cells. For the most effective use of this technique the researcher can draw upon basic information on factors that affect the brightness of the fluorescence image, and how well that image can be distinguished from background fluorescence or interfering fluorescence signals. A wide variety of fluorochromes are available, with emitting wavelengths that range from the blue-violet end of the visible spectrum to the infrared. Individual fluorochromes are characterized by their extinction coefficients, quantum yields, susceptibility to photobleaching, the wavelengths at which they maximally absorb excitatory and emit fluorescent light, and how far apart those wavelength maxima are separated. Additional choices for fluorescent labeling of antibodies are provided by the availability of fluorescent quantum dots. Informed choices of fluorochromes can obviate many problems, particularly with regard to situations in which two or more antigens are to be localized simultaneously within a specimen.

Variations in the neuropathology of familial Alzheimer's disease

Mutations in the amyloid precursor protein (APP), presenilin 1 (PSEN1) and presenilin 2 (PSEN2) genes cause autosomal dominant familial Alzheimer's disease (AD). PSEN1 and PSEN2 are essential components of the gamma-secretase complex, which cleaves APP to affect Abeta processing. Disruptions in Abeta processing have been hypothesised to be the major cause of AD (the amyloid cascade hypothesis). These genetic cases exhibit all the classic hallmark pathologies of AD including neuritic plaques, neurofibrillary tangles (NFT), tissue atrophy, neuronal loss and inflammation, often in significantly enhanced quantities. In particular, these cases have average greater hippocampal atrophy and NFT, more significant cortical Abeta42 plaque deposition and more substantial inflammation. Enhanced cerebral Abeta40 angiopathy is a feature of many cases, but particularly those with APP mutations where it can be the dominant pathology. Additional frontotemporal neuronal loss in association with increased tau pathology appears unique to PSEN mutations, with mutations in exons 8 and 9 having enlarged cotton wool plaques throughout their cortex. The mechanisms driving these pathological differences in AD are discussed.

Progression of hippocampal degeneration in amyotrophic lateral sclerosis with or without memory impairment: distinction from Alzheimer disease

The hippocampal involvement in amyotrophic lateral sclerosis (ALS) patients has been known for more than a decade, however, its relationship to clinical manifestations including memory deficits and topographical differentiation from Alzheimer disease (AD) remain unclear. In order to clarify the anatomopathological features in the hippocampus and their relevance to disease-specific memory deficits in ALS patients, topography and cytopathology of the hippocampal lesions along the perforant pathway were quantitatively and semiquantitatively surveyed in 14 ALS patients with extramotor involvement. These pathological findings were compared with clinical characteristics assessed from their clinical records. Cytoplasmic inclusions initially appear in the granular cells of the dentate gyrus (DG) and superficial small neurons of the transentorhinal cortex (TEC) with mild subicular degeneration (stage I: inclusion stage). Subsequent gliosis and neuronal loss of the TEC, concomitant with presynaptic degeneration of the outer molecular layer of the DG, suggests an extension of the degeneration through the perforant pathway (stage II: early perforant stage). In a more advanced stage, the presynaptic degeneration is more evident with moderate to severe neuronal loss in the TEC (stage III: advanced perforant stage). This advanced stage was associated with episodic memory deficits mimicking AD in some ALS patients. This ALS pathology initiated by cytoplasmic inclusions and neuronal loss in layer II-III of the TEC is different from neurofibrillary tangles of AD, dominant in layer II-III of the entorhinal cortex. Because this involvement of the TEC-molecular DG projection and subiculum is specific to ALS, it will provide a basis for clinical characterization of memory deficits of ALS, which could be distinct from those of AD.

Isoform-dependent immunolocalization of 14-3-3 proteins in developing rat cerebellum

We investigated the expression of 14-3-3 protein and its 7 isoforms during postnatal development of rat cerebellum with immunoblot and immunohistochemistry with isoform-specific antibodies. The relative amounts of total 14-3-3 protein, probed by an antibody (14-3-3 COM) recognizing a sequence shared among its isoforms, exhibited no significant changes from postnatal day 2 (P2) to P100. 14-3-3 COM-like immunoreactivity (IR), initially in the apical portion of Purkinje cells at P2, extended to Purkinje cell bodies at P14 and to their dendrites (P100) with increasing intensity. Molecular layer (after P7) and cerebellar nucleus neurons (after P14) were also immunolabeled with this antibody. These chronological changes were shared with those obtained with beta, gamma, and eta isoforms. In contrast, epsilon isoform-like IR was initially identified in processes of radial and Bergmann glia at P2 prior to its appearance in the molecular layer at P7 with subsequent intensification also in Purkinje cells after P14. Zeta and tau isoform-like IR was identified in the white matter and/or in oligodendroglial cells. The sigma isoform was the only isoform exhibiting a significant quantitative change with a peak at P14. Immunolocalization of sigma isoform was initially restricted in several cells in Purkinje cell layer at P2 and shifted to nuclei of external and internal granule cells and Purkinje cells after P14, whereas its immunolabeling was markedly weaker at P100. Different immunolocalizations of the 7 isoforms suggest that 14-3-3 protein isoforms individually associate with the neuronal and glial proliferation, differentiation, migration and development during postnatal formation of rat cerebellum.

Three-layered structure shared between Lewy bodies and lewy neurites-three-dimensional reconstruction of triple-labeled sections

Lewy bodies (LBs) and Lewy neurites (LNs) are the hallmarks of Parkinson's disease (PD). Although LBs and LNs, frequently coexistent, share some histological properties, their appearances are quite different under conventional two-dimensional observation. In order to clarify how these apparently different structures (LBs and LNs) are related during their formation, we performed three-dimensional observation on post-mortem brainstem tissues with PD. Sixty-microm thick floating sections were multi-immunofluorolabeled for alpha-synuclein (alphaS), ubiquitin (Ub) and neurofilament (NF). Serial confocal images were reconstructed with software. External three-dimensional configuration of LBs, double-labeled for alphaS and NF, exhibited frequent continuity with LNs (70%). Internally, alphaS and Ub formed the three-dimensional concentric inner layers and NF rimmed these inner layers. This layered structure was shared among spherical LBs, rod-shaped LNs and even convoluted forms of LBs/LNs. Furthermore, each layer exhibited continuity without interruption even in the convoluted form and around its junction to spherical LBs. This three-layered structure shared among various Lewy pathologies and their layered continuity on three-dimensional basis favor the hypothesis that LNs evolve into LBs. Besides progression from pale bodies to LBs, structural evolution from LNs into LBs may provide an alternative explanation for the variability of alphaS deposits and their interrelation.

Three-dimensional immunofluorescent double labelling using polyclonal antibodies derived from the same species: enterocytic colocalization of chylomicrons with Golgi apparatus

Double immunolabelling is a useful technique to determine cellular colocalization of proteins, but is prone to false-positive staining because of cross-reactivity between antibodies. In this study, we established a simple and quick method to demonstrate the immunofluorescent double labelling with two rabbit-derived polyclonal antibodies. The principle used was to establish a dilution of primary antibody for the first protein of interest, which would only be detectable following biotin-avidin amplification. Thereafter, the second protein of interest was assessed via standard secondary antibody detection, ensuring no cross-reactivity with the first protein antibody-antigen complex. We successfully demonstrated the three-dimensional colocalization of enterocytic apolipoprotein B, an equivocal marker of intestinal lipoproteins with Golgi apparatus. Colocalization of apo B and Golgi apparatus (75.2 +/- 8.5%) is consistent with the purported mode of secretion of these macromolecules.

Transient abundance of presenilin 1 fragments/nicastrin complex associated with synaptogenesis during development in rat cerebellum

Immunolocalization and expression of endogenous nicastrin (NCT) and presenilin 1 (PS1) fragments during postnatal development of rat cerebellum were investigated with fragment-specific antibodies. Immunoblotting for NCT revealed the expected mature and immature species, which gradually declined during development. In contrast, the expression of PS1 N-terminal fragment exhibited a peak at postnatal day 14 (P14) and declined thereafter. This chronological change was similarly observed with PS1 C-terminal fragment. Immunoprecipitation of NCT indicated its physical association with PS1 fragments. Colocalization of these molecules to the endoplasmic reticulum in cerebellar Purkinje cells indicates that they are organized into a complex in developing neurons. In addition, active sites of synaptogenesis, the base of the external granular layer and glomeruli, contained PS1 fragments and smaller amount of NCT. Isolated synaptic fraction contained both PS1 and NCT, suggesting their functional association within synapses. Transient abundance of NCT and PS1 fragments as a complex, when (P14) and where synaptogenesis is active, is consistent with intracellular trafficking of this complex in developing neurons and suggests its role as gamma-secretase in synaptogenesis.

Progressive accumulation of ubiquitin and disappearance of alpha-synuclein epitope in multiple system atrophy-associated glial cytoplasmic inclusions: triple fluorescence study combined with Gallyas-Braak method

Alpha-synuclein (alphaS) and ubiquitin (Ub) are shared constituents of glial cytoplasmic inclusions (GCIs) and Lewy bodies (LBs), both composed of fibrillary structures. Staining profiles of GCIs were investigated with triple immunofluorescence involving immunostaining for alphaS and Ub, both amplified with catalyzed reporter deposition, and a fluorochrome, thiazin red (TR) that has an affinity to fibrillary structures. After observation for the triple-fluorescent images, the sections were subsequently stained with the Gallyas-Braak method. Sections of putamen, cerebellar white matter and motor cortex from patients suffering from multiple system atrophy (MSA) with varying duration of the disease (4-15 years) were quantified for these staining profiles of Gallyas-positive GCIs. Although most of GCIs were positive for Ub and variably positive for alphaS, they were consistently negative for TR. The result was opposite in LBs in Lewy body disease with variable affinity to TR, suggesting that the construction of GCIs is different from that of LBs. These four staining features (alphaS, Ub, TR and Gallyas) alone failed to exhibit apparent correlation with disease duration, lesion site or severity of degeneration as reported previously. The fraction of alphaS-negative and Ub-positive GCIs, however, linearly increased along the disease progression, while that of alphaS-positive and Ub-negative GCIs decreased in contrast. This reciprocal change suggests that alphaS immunoreactivity in GCIs is being replaced by Ub immunoreactivity during the disease progression, which resulted in the ultimate predominance of alphaS-negative and Ub-positive GCIs in the most advanced case. Interestingly, this predominance of alphaS-negative and Ub-positive GCIs was a feature of motor cortex, where degeneration usually remains mild in spite of robust appearance of Gallyas-positive GCIs. Another fraction, alphaS-positive and Ub-positive GCIs were frequent in cerebellar white matter, suggesting that GCI evolution is heterogeneous and dependent also on area examined. Progressive accumulation of Ub with concomitant disappearance of alphaS epitope and their colocalization, partly shared with LBs, may represent a process of GCI formation, possibly linked to an aspect of degeneration in MSA.

Non-nuclear estrogen receptor beta and alpha in the hippocampus of male and female rats

Estrogens play important roles in the brain, acting through two receptor types, ERalpha and ERbeta, both recognized as transcription factors. In this study, we investigated the ERbeta mRNA and protein expression in the male and female rat brain, focusing on the hippocampus, and comparing with well-known ERalpha expression patterns. Extranuclear ERbeta localization, as shown by light microscopic immunocytochemistry and tissue fractionation experiments, was noted in the hippocampus, whereas nuclear ERbeta was present in the amygdala. Despite these marked differences in subcellular localizations, similar expression levels of ERbeta proteins as well as the profile of ERbeta mRNA isoforms were observed in the two brain structures. ERalpha was localized to the nucleus more so than ERbeta, yet not without an extranuclear component. Our results suggest that cytoplasmic estrogen receptors may play an important role in hippocampal physiology.

Exclusive induction of tau2 epitope in microglia/macrophages in inflammatory lesions-tautwopathy distinct from degenerative tauopathies

Tau2 antibody recognizes a phosphorylation-independent epitope that is pathologically modified as tau protein is phosphorylated to form neurofibrillary tangles of Alzheimer's disease (AD). Similar modification of tau2 epitope can be induced even in the absence phosphorylation of tau, as we first demonstrated in ischemic foci and in glial cytoplasmic inclusions (GCIs) of multiple system atrophy. This modification of tau2 epitope is distinguishable from those observed in degenerative tauopathies because (1) it is a conformational change, which is reversible upon exposure to a detergent; (2) it shows an absence of fibrils composed of phosphorylated tau protein; and (3) it is characterized by the lack of immunohistochemical labeling by anti-tau antibodies other than tau2. In this study, we expanded this observation to inflammatory foci of different pathologies (human immunodeficiency virus encephalopathy, progressive multifocal leukoencephalopathy or multiple sclerosis) by examining formalin-fixed, paraffin-embedded sections immunostained with a panel of anti-tau antibodies. It was found that tau2 was the only anti-tau antibody that immunolabeled microglia/macrophages in these lesions, and this immunoreactivity was reversibly diminished upon exposure to a detergent. Exclusive apparition of tau2 immunoreactivity in these cells without neurofibrillary pathology may be a secondary event shared with ischemic foci and GCIs. It is, however, related to a unique conformational state of tau, possibly grouped under the name of "tautwopathy", that may represent an initial stage of tau deposition distinct from degenerative tauopathies characterized by fibrils composed of phosphorylated tau protein.

Profound cardiac sympathetic denervation occurs in Parkinson disease

In the last few years, cardiac sympathetic dysfunction in Parkinson disease (PD) has been postulated on the basis of decreased cardiac uptake of sympathoneural imaging tracers. However, the pathological substrate for the dysfunction remains to be established. We examined the left ventricular anterior wall from postmortem specimens with immunohistochemical staining for tyrosine hydroxylase (TH), neurofilament (NF) and S-100 protein in PD patients and control subjects, and quantified the immunoreactive areas. As TH-immunoreactive axons nearly disappeared and NF-immunoreactive axons drastically decreased in number, the morphological degeneration of the cardiac sympathetic nerves in PD was confirmed. Quantitative analysis showed that sympathetic nerves were preferentially involved. Triple immunofluorolabeling for NF, TH, and myelin basic protein showed clearly the profound involvement of sympathetic axons in PD. The extent of involvement of the cardiac sympathetic nerves seems likely to be equivalent to that in the central nervous system, including the nigrostriatal dopaminergic system. PD affects the cardiac sympathetic nervous system profoundly as well as nigrostriatal dopaminergic system.

Application of antigen retrieval by heating for double-label fluorescent immunohistochemistry with identical species-derived primary antibodies

Double-label fluorescent immunohistochemistry (IHC) is frequently used to identify cellular and subcellular co-localization of independent antigens. In general, primary antibodies for double labeling should be derived from independent species. However, such convenient pairs of antibodies are not always available. To overcome this problem, several methods for double labeling with primary antibodies from identical species have been proposed. Among them are methods using monovalent secondary antibodies, such as Fab fragments. Soluble immune complexes consisting of primary and monovalent secondary antibodies are first formed. After absorption of the excess secondary antibody with nonspecific immunoglobulin, the immune complexes are applied to sections. By this procedure, unwanted cross-reaction between false pairs of antibodies is avoidable. However, soluble immune complexes often show reduced or no immunoreactivity to antigens on sections. I noted that antigen retrieval (AR) of tissues by heating often but not always showed improved immunoreactivity for soluble immune complexes. Here I demonstrate the examination of conditions for this soluble immune complex method using AR-treated sections and show examples of double-label fluorescent IHC with identical species-derived primary antibodies.

Dual enhancement of triple immunofluorescence using two antibodies from the same species

Triple immunofluorescence method with two mouse monoclonal antibodies and another rabbit polyclonal antibody was established with catalyzed reporter deposition (CARD) amplification on thick floating sections from the rat cerebellum. One of the monoclonal antibodies (anti-calbindin), diluted maximally, probed with anti-mouse IgG-horseradish peroxidase (HRP) and amplified with Cy5-conjugated tyramide, immunolabeled cerebellar Purkinje cells and their arborization. Subsequently, a rabbit polyclonal IgG (anti-glial fibrillary acidic protein (anti-GFAP)), probed with anti-rabbit IgG-HRP, amplified with biotin-tyramide and visualized with fluorescein-isothiocyanate (FITC)-streptavidin, immunolabeled Bergmann's glia. Another mouse monoclonal IgG (anti-SNAP25), probed with anti-mouse IgG-rhodamine without CARD amplification, selectively visualized synaptic sites, because the maximal dilution of the other monoclonal antibody (anti-calbindin) was below the detection threshold of this anti-mouse IgG-rhodamine. Separation of the two signals (calbindin and SNAP25), each detected through mouse monoclonal antibody, was then based on the difference of sensitivity either with or without CARD amplification. Triple immunofluorescence is possible when just one of the three primary antibodies is from different species. Intensification of two of the three signals provides further advantages to examine immunolocalization of multiple epitopes on histological sections.