The application of the avidin-biotin technique to previously stained histological sections

Microwave-Assisted Tissue Preparation for Rapid Fixation, Decalcification, Antigen Retrieval, Cryosectioning, and Immunostaining

Microwave irradiation of tissue during fixation and subsequent histochemical staining procedures significantly reduces the time required for incubation in fixation and staining solutions. Minimizing the incubation time in fixative reduces disruption of tissue morphology, and reducing the incubation time in staining solution or antibody solution decreases nonspecific labeling. Reduction of incubation time in staining solution also decreases the level of background noise. Microwave-assisted tissue preparation is applicable for tissue fixation, decalcification of bone tissues, treatment of adipose tissues, antigen retrieval, and other special staining of tissues. Microwave-assisted tissue fixation and staining are useful tools for histological analyses. This review describes the protocols using microwave irradiation for several essential procedures in histochemical studies, and these techniques are applicable to other protocols for tissue fixation and immunostaining in the field of cell biology.

A comparative study of cell proliferation markers in breast carcinomas

Aims-To investigate the tumour cell proliferative index obtained by immunostaining of paraffin wax sections of 30 cases of breast carcinoma with monoclonal antibodies MIB1, KiS1 and KiS5, and polyclonal Ki67 antisera to the Ki67 antigen and 19A2 and PC10 antibodies to proliferating cell nuclear antigen and the possible correlation between these indices and that of monoclonal Ki67 antibody in frozen sections of the same tumours.Methods-All tumour samples had been uniformly fixed and processed and sections were subjected to microwave antigen retrieval before immunostaining in all instances except for monoclonal Ki67 antibody which was used in cryostat sections. Tumour cell proliferative indices were evaluated by two independent examiners, each counting 500 tumour cells with the aid of a cross-hatched grid.Results-Proliferative indices obtained with MIB1, polyclonal Ki67, KiS1, and KiS5 correlated with those obtained with monoclonal Ki67 in frozen sections. Proliferative indices obtained with monoclonal 19A2 and PC10 showed no correlation with those of monoclonal Ki67 antibody. The staining obtained with MIB1 was the most intense and the easiest to read.Conclusions-Monoclonal antibodies MIB1, KiS1 and KiS5 and polyclonal Ki67 antiserum appear to be suitable substitutes for monoclonal antibody Ki67 in the assessment of tumour cell proliferative index. As these reagents are all immunoreactive in paraffin wax sections, they overcome the requirement for frozen tissue for immunostaining with monoclonal Ki67.

Immunostaining of cell preparations: a comparative evaluation of common fixatives and protocols

Immunostaining of cytologic preparations has been beset by problems of inconsistency, high background staining, and the requirement of different fixatives for different antigens. This study sought to identify a universal fixative and a simple fixation protocol suitable for a wide range of tissue antigens commonly employed for cytologic diagnosis. In an analysis of 23 fixation protocols involving acetone, acetone/methanol, acetone/formalin, glutaraldehyde, ethanol, methanol, and formal saline, fixation in 0.1% formal saline overnight at 27 degrees C followed by 10 min fixation in 100% ethanol produced the most consistent and optimal preservation of immunoreactivity which could be further enhanced by pre-treatment with microwaves for epitope retrieval. Blocking of endogenous peroxidase was not necessary with this fixation protocol. Provided the smears were well air-dried (for at least 14 hr) prior to immersion in formal saline, there was no need to employ adhesive-coated glass slides. The smears could be kept at 27 degrees C (room temperature) for at least 7 days and at -70 degrees C for 5 wk without loss of immunoreactivity as air-dried smears or after fixation in formal saline. One hundred percent acetone and 100% ethanol produced good morphology and immunoreactivity but a high level of background staining, whereas acetone-based mixtures resulted in inconsistent immunostaining.

Brain and spinal cord lesions in encephalitozoonosis in mink

Central nervous system lesions were studied by light microscopy in 43 farmed mink, aged 5 months to 2 1/2 years, with spontaneous encephalitozoonosis and showing cataractous eye changes. Lesions were found in the brain and spinal cord of all animals examined but were generally mild and chronic. The lesions were consistent with those previously described in spontaneous encephalitozoonosis in other carnivores. Parasites in parasitophorous vacuoles and free or phagocytosed in necrotic and granulomatous lesions were demonstrated in animals aged 5 months to 1 year. The occurrence of arterial lesions of the polyarteritis nodosa type found in the youngest animals probably indicates fetal infection. In animals aged 1 1/2 and 2 1/2 years active lesions were usually lacking and the changes were characterized by arterial sclerosis, sometimes with aneurysmal formations, small perivascular lympho-plasmacytic cuffings and focal gliosis.

A retrospective survey of endocardial proliferative lesions in rats

Sixty, proliferative, endocardial lesions were diagnosed in 19,304 rats, for an overall incidence of 0.3%. This population consisted of 10,127 Fischer 344, 8,737 Wistar, 200 Sprague-Dawley, and 240 Long Evans rats from chronic/oncogenicity studies reported at Lilly Research Laboratories from 1976 to 1988. Of the 60 proliferative lesions, 44 were classified as endocardial hyperplasia, 15 as endocardial schwannomas, and one as an endocardial sarcoma for prevalence rates of 0.2%, 0.08%, and 0.005%, respectively. Affected rats ranged in age from 42 to 110 weeks. There were no sex or treatment-related differences in the prevalence of the rat endocardial proliferative lesions. A review of endocardial lesions in 18 of 233 Wistar rats treated with carbamate derivatives revealed endocardial hyperplasia in 12 rats, schwannomas in five rats, and a sarcoma in one rat. One of the 12 rats with endocardial hyperplasia also had an intramural schwannoma. Of 200 Wistar rats given N-nitroso-N-methylurea, two had endocardial hyperplasia, and one had an endocardial schwannoma. Morphologic features were similar in either spontaneous or treatment-associated hyperplasia or neoplasia of the rat endocardium. Probable Schwann cell origin of the endocardial proliferative lesions was indicated by positive immunohistochemical staining for S-100 antigen in 10/12 spontaneous and 11/14 carcinogen-associated endocardial hyperplastic lesions. Further, 15/16 spontaneous and 6/7 carcinogen-associated neoplasms were immunoreactive to S-100. No tumor metastasis was recorded in either the spontaneously affected or carcinogen-treated rats.

Immunohistochemical detection of papillomavirus structural antigens in animal hyperplastic and neoplastic epithelial lesions

One hundred and seventy-two hyperplastic and neoplastic epithelial lesions from 8 different mammalian and 1 avian species have been tested with an immunohistochemical technique to detect papillomavirus structural antigens. Selected lesions were diagnosed histologically as papilloma, fibropapilloma, equine sarcoid, squamous cell carcinoma, basalioma, epulis, keratoacanthoma, trichoepithelioma, pilomatrixoma, epidermal inclusion cyst, and hyperkeratotic or acanthotic epidermal lesions. Positive nuclear staining was detected in 14 out of 23 papillomas, 8 out of 32 fibropapillomas and in 1 out of 3 hyperplastic epidermal lesions. Positive samples were found in 5 of 8 mammalian species. Selected samples were also examined by transmission electron microscopy. In 4 samples papillomavirus was seen. In two other samples, negative with immunoperoxidase technique, papovavirus-like particles were observed.

Neuropathology and host-parasite relationship of acute experimental toxoplasmosis of the blue fox (Alopex lagopus)

The neuropathology and host-parasite relationship of experimental infection with the RH-strain of Toxoplasma gondii were studied in 27 blue foxes (Alopex lagopus) aged 0 to 23 days, using light microscopy, including immunohistochemical staining, and transmission and scanning electron microscopy. All cases displayed multifocal necrotic lesions with numerous parasitic tachyzoites in the brain and spinal cord. The gray matter and the meninges were most seriously affected. Although a wide variety of cell types were parasitized, neurons and astrocytes seemed to be the main target cells. Individual parasitophorous vacuoles usually contained only a few tachyzoites, with rosette formations as a prominent feature. The present ultrastructural study supports the theory that the parasites actively invade the host cells by mechanisms that are different from those of phagocytosis. This is apparently the first report indicating that the formation of the network of tubular structures within the parasitophorous vacuole of T. gondii is associated with a transient, sack-like formation in the posterior end of the tachyzoites.

The neuropathology in toxoplasmosis-like infection caused by a newly recognized cyst-forming sporozoon in dogs

The pathomorphological changes in the central nervous system associated with an infection with a previously reported, Toxoplasma-like, cyst-forming sporozoon were studied by means of light microscopy, including immunohistochemistry, and transmission electron microscopy in seven dogs, aged 4 months to 2 years. Tachyzoites (endozoites) within parasitophorous vacuoles were found in neurons, astrocytes, macrophages, vascular pericytes and probably also in fibroblasts, while cyst stages were only observed in cells showing features of neurons. Proliferating tachyzoites were associated with lesions of a necrotic/granulomatous type. Perivascular accumulations of lymphocytes and plasma cells, together with an activation of astrocytes and perivascular fibroblasts resulting in marked sclerosis, were prominent features in all cases. The grey matter was most seriously affected in the brain, while the white matter was most often the site of inflammation in the spinal cord. The structural similarity to the newly reported Neospora caninum suggests that we are dealing here with the same parasite. However, the present infection and toxoplasmosis have so many features in common, including the light microscopical morphology of the organisms and host/parasite relationship, that a definite etiological diagnosis should be based on ultrastructural and/or immunohistochemical examinations.

Use of the avidin-biotin-peroxidase immunostaining technique on previously stained histologic sections

A recent report has demonstrated that the avidin-biotin-peroxidase (ABP) technique can successfully be used on previously stained histologic sections without the loss of sensitivity. In this study the tissues had been microwave fixed and only H & E stained sections were used. This procedure was tested on formalin-fixed tissues previously stained with H & E, PAS and van Gieson. Stained sections were prepared from selected blocks used as controls. One week after staining the sections were decolorized and together with the unstained control sections were restained with the ABP technique using IgA, IgD, IgE, IgM, kappa and lambda light chains, S100, EMA, LCA, amylase and PCK antisera. Demonstration of the tissue antigens was best with the previously stained H & E slides with little or no loss in sensitivity. Variable results were obtained with the PAS and van Gieson slides, the loss of sensitivity varying from none to complete.