Immunohistochemistry on resin sections: a comparison of resin embedding techniques for small mucosal biopsies

Cyclosporin A treatment and airways inflammation in corticosteroid-dependent asthma

Cyclosporin A is a potent immunosuppressive agent which inhibits activation of T cells and other inflammatory cells. It has been shown to be of clinical benefit in patients with corticosteroid-dependent asthma, but there are no data on its in vivo effects on airways inflammation. In this report, we describe the case of a 47-year-old man with chronic severe corticosteroid-dependent asthma who made a dramatic clinical response to therapy with cyclosporin A. Fibreoptic bronchoscopy with bronchoalveolar lavage and endobronchial biopsy were performed before and after a 12-month period of treatment with cyclosporin A and demonstrated a concomitant reduction in airway inflammatory indices.

Seasonal allergic conjunctivitis is accompanied by increased mast cell numbers in the absence of leucocyte infiltration

BACKGROUND

Seasonal allergic conjunctivitis (SAC) is the most common allergic disease to affect the eye, occurring alone or in association with allergic rhinitis. Infiltration with mast cells and eosinophils is characteristic of the chronic forms of allergic conjunctivitis such as vernal and atopic keratoconjunctivitis, and these cell types also contribute significantly to allergic inflammation in the skin. Indirect evidence for a similar pattern of cellular events in SAC comes from studies which demonstrate raised eosinophil and neutrophil numbers in conjunctival scrapings and elevated levels of mast cell tryptase in tears following allergen challenge.

OBJECTIVE

To directly characterize the inflammatory cell infiltrate in SAC and to determine its clinical relevance.

METHODS

We employed specific immunohistochemical staining to count mast cells, eosinophils and neutrophils in the conjunctival epithelium and lamina propria of eight atopic patients with SAC in, and 12 SAC patients out of the hay fever season. Sixteen patients with no history of ocular allergy were used as control subjects.

RESULTS

Mast cells were absent from normal epithelium. During the pollen season median mast cell numbers in the lamina propria were found to be increased by 61% in patients with SAC compared with normals (P=0.012). Eosinophils were found in the lamina propria in less than half of the symptomatic patients with SAC and in only three patients were eosinophils present in the epithelium. The neutrophil numbers in the lamina propria of patients with SAC tended to be higher than normals but these changes did not reach statistical significance.

CONCLUSION

These data based on the direct assessment of conjunctival tissue provide evidence that symptoms occur in SAC in the absence of detectable recruitment of eosinophils or neutrophils. This suggests that this disorder is related to mast cell-mediated changes.

The inflammatory effects of 2 ppm NO2 on the airways of healthy subjects

Nitrogen dioxide (NO2) is a free radical and a common oxidant in polluted air. Here we present data on the time course of inflammation after NO2 exposure, as reflected in bronchial biopsy and airway lavage specimens. Healthy, nonsmoking subjects were exposed to air or 2 ppm NO2 for 4 h in random order on separate occasions. Endobronchial biopsies, bronchial washing (BW), and bronchoalveolar lavage (BAL) were done at 1.5 h (n = 15) or 6 h (n = 15) after exposure. In BW, exposure to NO2 induced a 1.5-fold increase in interleukin-8 (IL-8) (p < 0.05) at 1.5 h and a 2.5-fold increase in neutrophils (p < 0.01) at 6 h. In BAL fluid (BALF), small increases were observed in CD45RO+ lymphocytes, B-cells, and natural killer (NK) cells only. Immunohistologic examination of bronchial biopsy specimens showed no signs of upregulation of adhesion molecules, and failed to reveal any significant changes in inflammatory cells at either time point after NO2 exposure. In summary, NO2 induced a neutrophilic inflammation in the airways that was detectable in BW at 6 h after NO2 exposure. The increase in neutrophils could be related to the enhanced IL-8 secretion observed at 1.5 h after exposure. The absence of adhesion-molecule upregulation or cellular inflammation in mucosal biopsy specimens indicates that the major site of inflammation following exposure to NO2 may be in the smaller airways and not in the alveoli.

Transforming growth factor-beta 1 in asthma. Measurement in bronchoalveolar lavage fluid

Airway wall remodeling is an established pathological feature in asthma. Its causes are not well understood, but one mediator of potential relevance is transforming growth factor-beta 1 (TGF-beta 1). We have measured levels of immunoreactive TGF-beta 1 in bronchoalveolar lavage (BAL) fluid from clinically stable atopic asthmatics and healthy control subjects. We have also examined the influence of allergen exposure on TGF-beta 1 release in the airways using a segmental bronchoprovocation model, with BAL performed at two time points following endobronchial allergen and sham saline challenges. Basal concentrations of TGF-beta 1 were significantly higher in asthmatics than control subjects (median 8.0 versus 5.5 pg/ml, p = 0.027). Following segmental bronchoprovocation, concentrations of TGF-beta 1 at the allergen- and saline-challenged sites were not significantly different after 10 min, (31.3 versus 25.0 pg/ml, p = 0.78), but after 24 h there were significantly higher TGF-beta 1 concentrations at the allergen-challenged sites (46.0 versus 21.5 pg/ml, p = 0.017). We conclude that basal TGF-beta 1 levels in the airways are elevated in atopic asthma and that these levels increase further in response to allergen exposure. These findings are consistent with the hypothesis that TGF-beta 1 is implicated in airway wall remodeling in asthma.

Embedding of bone samples in methylmethacrylate: an improved method suitable for bone histomorphometry, histochemistry, and immunohistochemistry

Methylmethacrylate (MMA) embedding of undecalcified bone biopsies is a technique widely used for bone histomorphometry. However, conventional MMA embedding causes almost complete loss of enzyme activity and protein antigenicity in the tissues. Recently, an MMA embedding technique has been reported that preserves enzyme activity and antigenic determinants in bone tissue. We describe here a modification of this embedding method. For our modified MMA embedding process, commercially available methacrylates can be used without purification, and the histologic quality of bone sections is comparable to that of conventionally MMA-embedded bone specimens. The technique reported here can be employed for embedding of larger bone samples and is suitable for histochemical and immunohistological applications as well as for routine bone histomorphometry. By addition of methylbenzoate during infiltration and polymerization of the plastic, the antigenicity of the tissue was improved. As applications of this novel technique, demonstration of alkaline phosphatase and tartrate-resistant acid phosphatase as well as positive labeling of Kupffer cells and osteoclasts with the monoclonal antibody ED1 in sections of liver, tibiae, and vertebrae of 3-month-old rats was demonstrated. The method described here might be useful for the inclusion of histochemical and immunohistological methods into bone histomorphometry.

Phenotypic characterization of T cells infiltrating the conjunctiva in chronic allergic eye disease

BACKGROUND

Chronic allergic conjunctivitis comprises a spectrum of diseases including atopic keratoconjunctivitis, atopic blepharoconjunctivitis, vernal keratoconjunctivitis, and contact lens-associated giant pupillary conjunctivitis. Each condition is characterized by a complex immunopathology with a mixed cellular infiltrate. Treatment with conventional mast cell stabilizers is often unsatisfactory, and therapy depends heavily on topical corticosteroids.

OBJECTIVE

Recent evidence suggests that T lymphocytes play an important role in mediating the immunopathology seen in the chronic allergic response in the skin and the lungs.

METHODS

We have therefore investigated the prevalence of T cells and their subsets in the different chronic allergic eye conditions by means of immunohistochemistry.

RESULTS

We found significantly increased numbers of CD4+, CD45RO+, and HLA-DR+ T cells in the conjunctiva of patients with atopic and vernal keratoconjunctivitis and giant papillary conjunctivitis, with a corresponding upregulation of markers present on antigen presenting cells.

CONCLUSIONS

These findings suggest that like allergic conditions in the skin and lungs, CD4+ memory T cells are involved in the regulation of the immunopathology of chronic allergic eye responses. Further characterization of these T cells will provide the information necessary for future immunotherapeutic interventions.

Immunohistochemical detection of GM-CSF, IL-4 and IL-5 in a murine model of allergic bronchopulmonary aspergillosis

BACKGROUND

Granulocyte macrophage-colony stimulating factor (GM-CSF), interleukin-4 (IL-4) and IL-5 are important in tissue eosinophil accumulation and high IgE production in allergic inflammatory reaction.

OBJECTIVE

We examine lung GM-CSF, IL-4 and IL-5 expression in a murine model of allergic bronchopulmonary aspergillosis (ABPA) characterized by eosinophil and lymphocyte lung infiltration and elevated serum IgE level.

METHODS

C57BL/6 mice were intranasally treated three times a week for 1, 2 or 3 week(s) with Aspergillus fumigatus (Af) antigen or saline and were sacrificed on days 7, 14 and 21. Immunohistochemical analyses for GM-CSF, IL-4 and IL-5 were performed on lung sections.

RESULTS

Af treatment induced a remarkable pulmonary eosinophil influx. Increased numbers of lung T lymphocytes and GM-CSF positive cells were observed on days 14 and 21. IL-4 and IL-5 positive cells were increased significantly only on day 14. Immunostained serial sections showed that most (> or = 98%) cytokine positive cells were CD3 positive. Few eosinophils (< 2% of cytokine positive cells) were immunoreactive for GM-CSF and IL-5. Significant correlations were found between the number of GM-CSF and IL-5 positive cells, and the number of eosinophils in Af-treated lung (r = 0.62, P < 0.05 and r = 0.52, P < 0.05 respectively), and between the number of IL-4 positive cells and the serum total IgE level (r = 0.64, P < 0.01).

CONCLUSIONS

Our data suggest a role for T lymphocyte GM-CSF, IL-4 and IL-5 in Af-induced mouse pulmonary eosinophilia and increased serum IgE production and further support the importance of T helper (TH2) cells in the pathogenesis of ABPA.

TNF alpha is localized to nasal mucosal mast cells and is released in acute allergic rhinitis

Allergic mucosal inflammation is characterized by tissue infiltration with eosinophils, and associated activation of mast cells and T lymphocytes. Tumour necrosis factor (TNF) alpha/cachectin is a candidate cytokine relevant to the pathogenesis of these events through its capacity to upregulate the expression of endothelial cell adhesion molecules, mediate granulocyte chemoattraction, and activate eosinophils, mast cells and T cells. To investigate the presence and localization of TNF alpha in the nasal mucosa in allergic rhinitis, nasal biopsies from perennial rhinitic (n = 13) and non-rhinitic volunteers (n = 11) were embedded in glycol methacrylate and immunostained with a monoclonal antibody directed against TNF alpha, and adjacent 2 microns sections stained for tryptase, CD3 and eosinophil cationic protein. This identified positive immunostaining for TNF alpha in the submucosa of both the rhinitic and normal subjects (median cell counts 13 and 23 cells/mm2 respectively, P = 0.24) with cellular localization to mast cells but not to T-lymphocytes or eosinophils. In a subsequent study of seven atopic subjects, nasal allergen challenge produced increases in lavage levels of histamine and albumin, which was associated with significant release of TNF alpha as early as 2 min post-allergen when compared with the saline control day (P = 0.05). This difference was also apparent when studying the area under the curve both at 30 and 60 min post-challenge t-test (P = 0.015 and 0.02 respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Mast cell distribution and neutral protease expression in acute and chronic allergic conjunctivitis

Allergic eye disease has a variety of clinical manifestations including seasonal atopic conjunctivitis (SAC), perennial atopic conjunctivitis (PAC), atopic keratoconjunctivitis (AKC), and atopic blepharoconjunctivitis (ABC). We have investigated the number, distribution and protease expression of mast cells in normal and diseased conjunctiva with the use of immunohistochemistry in water-miscible resin sections. The median mast cell densities in normal subjects were 17 mm-2 in the bulbar substantia propria and 9 mm-2 in tarsal substantia propria. Mast cells were absent from the normal conjunctival epithelium at both sites. Mast cell densities were increased in the bulbar substantia propria in SAC, AKC and ABC. Tarsal substantia propria showed a significant increase in mast cells in ABC and AKC disease states. Mast cells express a range of proteases which varies according to their anatomic site. Mast cells in connective tissue are described to contain tryptase, chymase, cathepsin-G and carboxypeptidase-A, whereas mucosal mast cells contain only tryptase. In the diseased conjunctiva there was a marked reduction in proteases other than tryptase in the intraepithelial mast cells. There were also significant reductions in protease expression other than tryptase in the bulbar substantia propria in AKC and ABC. There appear to be specific alterations in the distribution of mast cells in the sub-categories of allergic eye disease. The distinction between mucosal and connective tissue mast cell phenotypes is not clear-cut and may depend on the functional state of the mast cells in relation to the microenvironment.

Cytokines in the conjunctiva of acute and chronic mucous membrane pemphigoid: an immunohistochemical analysis

The aim of this study was to evaluate the potential role of certain soluble factors in conjunctival scar tissue formation of pemphigoid patients. Epibulbar conjunctival biopsy specimens were taken from patients with acute ulcerative (n = 4), subacute (n = 8) and chronic (n = 8) mucous membrane pemphigoid and from twelve age-matched healthy individuals. The tissues were embedded in glycol methacrylate and analysed by immunohistochemical methods. Interleukin-2 (IL-2), interferon-gamma, transforming growth factor-beta (TGF-beta), platelet-derived growth factor (PDGF), basic fibroblast growth factor (bFGF), tumour necrosis factor-alpha and proliferating cells (as identified with the antibody Ki-67) were found in both pemphigoid patients and normal controls. Interleukin-4 was not found with this method in either normal or diseased conjunctiva. Significant differences between normal and diseased conjunctiva were found for TGF-beta and for proliferating cells, which were both increased in the acute disease group. More intense staining was found in the subacute disease group for IL-2, bFGF and PDGF. Our findings showed that a variety of cytokines were present in normal and diseased bulbar conjunctiva. Acute conjunctival disease in mucous membrane pemphigoid may indicate active scar tissue formation, implied by an increase in TGF-beta and the presence of proliferating fibroblasts.