Histamine immunohistochemistry: a new and highly sensitive method for studying cutaneous mast cells

Modern Imaging Technologies of Mast Cells for Biology and Medicine (Review)

Mast cells play an important role in the body defense against allergens, pathogens, and parasites by participating in inflammation development. However, there is evidence for their contributing to the pathogenesis of a number of atopic, autoimmune, as well as cardiovascular, oncologic, neurologic, and other diseases (allergy, asthma, eczema, rhinitis, anaphylaxis, mastocytosis, multiple sclerosis, rheumatoid arthritis, inflammatory gastrointestinal and pulmonary diseases, migraine, etc.). The diagnosis of many diseases and the study of mast cell functions in health and disease require their identification; so, the knowledge on adequate imaging techniques for mast cells in humans and different species of animals is of particular importance. The present review summarizes the data on major methods of mast cell imaging: enzyme histochemistry, immunohistochemistry, as well as histochemistry using histological stains. The main histological stains bind to heparin and other acidic mucopolysaccharides contained in mast cells and stain them metachromatically. Among these are toluidine blue, methylene blue (including that contained in May-Grünwald-Giemsa stain), thionin, pinacyanol, and others. Safranin and fluorescent dyes: berberine and avidin - also bind to heparin. Longer staining with histological dyes or alcian blue staining is needed to label mucosal and immature mast cells. Advanced techniques - enzyme histochemistry and especially immunohistochemistry - enable to detect mast cells high-selectively using a reaction to tryptases and chymases (specific proteases of these cells). In the immunohistochemical study of tryptases and chymases, species-specific differences in the distribution of the proteases in mast cells of humans and animals should be taken into account for their adequate detection. The immunohistochemical reaction to immunoglobulin E receptor (FcεRI) and c-kit receptor is not specific to mast cells, although the latter is important to demonstrate their proliferation in normal and malignant growth. Correct fixation of biological material is also discussed in the review as it is of great significance for histochemical and immunohistochemical mast cell detection. Fluorescent methods of immunohistochemistry and a multimarker analysis in combination with confocal microscopy are reported to be new technological approaches currently used to study various mast cell populations.

Challenges in Developing a Biochip for Intact Histamine Using Commercial Antibodies

This study describes the development and the challenges in the development of an on-chip immunoassay for histamine using commercially available antibodies. Histamine can be used as an indicator of food freshness and quality, but it is also a relevant marker in clinical diagnostics. Due to its low molecular weight, simple structure and thus low immunogenicity production of high specificity and affinity antibodies is difficult. From six commercial anti-histamine antibodies tested, only two bound the histamine free in the solution. A fluorescent on-chip immunoassay for histamine was established with a dynamic range of 8–111 µg/mL using polyclonal anti-histamine antibody H7403 from Sigma (Mendota Heights, MN, USA). The anti-histamine antibodies described and used in published literature are thoroughly reviewed and the quality of commercial antibodies and their traceability and quality issues are highlighted and extensively discussed.

Cutaneous mast cells are altered in normal healthy volunteers sitting in front of ordinary TVs/PCs--results from open-field provocation experiments

BACKGROUND

Considerable controversy has surrounded the question of possible biological responses to electromagnetic fields (EMFs) generated from visual display terminals (VDTs), such as personal computers (PCs) and ordinary television sets (TVs). The cellular and molecular mechanisms for such potential harmful health hazards have not yet been understood, although clues from the literature include mast cells and histamine. The aim of this study was therefore to investigate possible biological mast cell responses to TV/PC screens.

METHODS

Using the indirect immunofluorescence technique, we studied the presence of histamine-containing mast cells in the dermis of healthy volunteers. Cutaneous biopsies taken before and after exposure to ordinary TV/PC screens for 2 or 4 h were investigated in 13 healthy subjects.

RESULTS

Our present in vivo study indicates that normal cutaneous mast cells could be altered by exposure from ordinary TV/PC screens. To our great surprise, we found the number of mast cells in the papillary and reticular dermis to increase, to varying degrees, in 5 out the 13 subjects after such an exposure. A migration of mast cells towards the uppermost dermis appeared as the most important event. Thus, the normally upper "empty zone" of the dermis disappeared, and instead, a higher density of mast cells were found in this zone. These cells also seemed to have a tendency to increase in number towards the epidermal-dermal junctional zone and some of them lost their granular content and the cytoplasm shrunk (=degranulation). These findings could only be seen in the exposed skin. Two of the 13 cases instead showed a decrease in mast cell number, but the shift in mast cells towards the upper dermis was still visible. Twenty-four h after the provocation, the cellular number and location were normalized in all subjects.

CONCLUSIONS

By definition, normal healthy volunteers are assumed not to react to a TV/PC screen provocation. To our great surprise, this proved not to be true. The present results might lay a foundation to understand the underlying cause of so-called "screen dermatitis" with special reference to mast cells. However, blind or double-blind experiments using patients ought to be further investigated in order to find out the exact cause for the observed changes. Such causes include the effects of surrounding airborne chemicals, stress factors, etc.

Histamine immunocytochemistry: a new method for detection of basophils in peripheral blood

We report that basophils in peripheral blood can be stained using histamine immunocytochemistry. The staining is based on the fixation of leucocytes with 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (CDI) and the subsequent incubation of these cells with antisera raised against histamine conjugated to different carrier proteins using CDI. The staining appears to be specific for basophils and stained cells can be examined using both fluorescence microscopy and flow cytometry. In addition, histamine immunocytochemistry can be combined with conventional immunocytochemistry by incubating leucocytes with antibodies to cell surface antigens prior to or following fixation of the cells with CDI. Thus, histamine immunocytochemistry may be a valuable tool in future studies of human basophils.

A theoretical model based upon mast cells and histamine to explain the recently proclaimed sensitivity to electric and/or magnetic fields in humans

The relationship between exposure to electromagnetic fields (EMFs) and human health is more and more in focus. This is mainly because of the rapid increasing use of such EMFs within our modern society. Exposure to EMFs has been linked to different cancer forms, e.g. leukemia, brain tumors, neurological diseases, such as Alzheimer's disease, asthma and allergy, and recently to the phenomena of 'electrosupersensitivity' and 'screen dermatitis'. There is an increasing number of reports about cutaneous problems as well as symptoms from internal organs, such as the heart, in people exposed to video display terminals (VDTs). These people suffer from subjective and objective skin and mucosa-related symptoms, such as itch, heat sensation, pain, erythema, papules and pustules. In severe cases, people can not, for instance, use VDTs or artificial light at all, or be close to mobile telephones. Mast cells (MCs), when activated, release a spectrum of mediators, among them histamine, which is involved in a variety of biological effects with clinical relevance, e.g. allergic hypersensitivity, itch, edema, local erythema and many types of dermatoses. From the results of recent studies, it is clear that EMFs affect the MC, and also the dendritic cell, population and may degranulate these cells. The release of inflammatory substances, such as histamine, from MCs in the skin results in a local erythema, edema and sensation of itch and pain, and the release of somatostatin from the dendritic cells may give rise to subjective sensations of on-going inflammation and sensitivity to ordinary light. These are, as mentioned, the common symptoms reported from patients suffering from 'electrosupersensitivity'/'screen dermatitis'. MCs are also present in the heart tissue and their localization is of particular relevance to their function. Data from studies made on interactions of EMFs with the cardiac function have demonstrated that highly interesting changes are present in the heart after exposure to EMFs. One could speculate that the cardiac MCs are responsible for these changes due to degranulation after exposure to EMFs. However, it is still not known how, and through which mechanisms, all these different cells are affected by EMFs. In this article, we present a theoretical model, based upon observations on EMFs and their cellular effects, to explain the proclaimed sensitivity to electric and/or magnetic fields in humans.

Histamine content and secretion in basophils and mast cells

Biochemical determinations of the histamine content and secretion from basophils and mast cells have been available for some time, and much of the complex anatomy of these cellular populations and their release reactions has been documented using the electron microscope. The ultrastructural analyses led to the description of vesicular transport between secretory granules and the plasma membrane as a mechanism for secretion from basophils and mast cells--a process termed piecemeal degranulation. Proof of concepts incorporated in a general degranulation model put forth in 1975 (DVORAK, H.F. and DVORAK, A.M.) requires high magnification imaging of a granule constituent in trafficking vesicles in the process of a stimulated release reaction in which the constituent release is monitored biochemically. Development and application of a new enzyme-affinity method to detect histamine at high magnifications in well-preserved ultrastructural samples have provided the necessary means to establish proof that appropriate secretagogues can stimulate the vesicular transport of histamine in basophils and mast cells during release reactions monitored biochemically. The background information necessary to the understanding of this result is presented here, as well as the development and verification of the diamine oxidase-gold method to image histamine in human mast cell granules as the test system. Also presented are applications using this technology to examine histamine stores and secretion in vitro, in vivo, and ex vivo in human basophils and mast cells and in mouse mast cells. Specifically examined are histamine stores developing in maturing mast cells induced to develop de novo from cultured human cord blood cells, secretagogue-stimulated release and recovery of histamine stores from isolated, purified human lung mast cells ex vivo, cytokine-stimulated degranulation of human skin mast cells and their histamine stores in vivo, piecemeal degranulation of human gut mast cells and their histamine stores in inflammatory bowel disease in vivo, piecemeal degranulation of mouse skin mast cells and their histamine stores in inflammatory eye disease in an interleukin-4 transgenic mouse model in vivo, and the stimulated secretion and recovery of histamine from human basophils ex vivo.

Histamine-containing mast cells and their relationship to NGFr-immunoreactive nerves in prurigo nodularis: a reappraisal

The mast cell, which is a histamine-containing cell, has been found to have far more functions in skin inflammation than hitherto understood. To investigate the appearance of mast cells in prurigo nodularis, histamine immunohistochemistry in combination with nerve growth factor receptor (NGFr) double-staining as well as electron microscopic studies were performed. The results revealed that the histamine-containing cell number was increased in the lesional dermis. The mast cell size was also increased and the shape had become more dendritic. They tended to contact the epidermis and even infiltrated into it. In the histamine and NGFr double-staining, both an increased histamine-containing mast cell number and an increased number of NGFr-immunoreactive nerve fiber profiles were revealed in the upper dermis of the prurigo nodularis lesional skin. Mast cells were seen in close vicinity to NGFr-positive nerves and sometimes even seemingly to contact single nerve fibers. At the ultrastructural level, it is obvious that the mast cell bodies become larger, having more abundant cytoplasm and organelles (e.g. mitochondria), but comparatively fewer characteristic granules. Mast cells were often observed to sprout long dendrites, with or without granules. The cells were also frequently seen to contact other cell types, and a mast cell infiltration into the epidermis was also found. The statistical results of mast cell numbers showed a significant increase in prurigo nodularis lesional skin compared to the normal controls. The present results further indicate that mast cells, together with cutaneous nerve fibers, are actively involved in the pathogenesis of the disease.

Histaminergic nerves demonstrated in the skin. A new direct mode of neurogenic inflammation?

An intradermal administration of histamine into human skin results in a local erythema, edema and often also the sensations of itch and/or pain. These effects have classically been attributed to the presence of histamine-containing mast cells. However, in the present investigation, we report the observation of histamine-immunoreactive nerves in the skin of Sprague-Dawley rats using a new and highly sensitive immunohistochemical approach. These data suggest a more direct route of cutaneous histamine effects, mediated exclusively by the peripheral nervous system. The findings could also give a new basis for explaining histamine-related issues, such as itch.

Skin changes in patients claiming to suffer from "screen dermatitis": a two-case open-field provocation study

An open-field provocation, in front of an ordinary TV set, of 2 patients regarding themselves as suffering from skin problems due to work at video display terminals (VDTs) is presented. Using immunohistochemistry, in combination with a wide range of antisera directed towards cellular and neurochemical markers, we were able to show a high-to-very high number of somatostatin-immunoreactive dendritic cells as well as histamine-positive mast cells in skin biopsies from the anterior neck taken before the start of the provocation. At the end of the provocation the number of mast cells was unchanged; however, the somatostatin-positive cells had seemingly disappeared. The reason for this latter findings is discussed in terms of loss of immunoreactivity, increase of breakdown, etc. The high number of mast cells present may explain the clinical symptoms of itch, pain, edema and erythema. Naturally, in view of the present public debate, the observed results are highly provocative and, we believe, have to be taken seriously.

Histamine immunohistochemistry is superior to the conventional heparin-based routine staining methodology for investigations of human skin mast cells

Conventional studies of mast cells are limited by methodological restrictions such as a selective fixative-dependent routine staining blockage. This is thought to depend on the biochemical differences of the mast cell granule contents suggesting a cellular heterogeneity. Investigations of human mast cells, using routine methods, also suffer from the problem of a low signal-to-noise ratio. In the present study, normal human skin was used to compare an immunohistochemical method for histamine with two recommended mast-cell fixatives and a new commercial fixative in combination with three routine stains. Mast cells were found throughout the dermis with all the routine stains used. However, immunohistochemistry gave profoundly better results. Small structures, such as thin cytoplasmatic extensions and single granules, were readily detectable. Double-staining (immunohistochemistry followed by routine staining) revealed differences in staining capacity. All immunoreactive cells were not stained by routine stains and sometimes the opposite was also seen. This supports earlier reported evidence of heterogeneity, not only between skin and intestinal mast cells but also among skin mast cells themselves. Furthermore, by focusing on histamine, instead of heparin, we probably overcame the problems of the selective fixative-dependent routine staining blockage. Finally, the immunofluorescence technique provides a high signal-to-noise ratio and is an excellent method for making high-quality microphotographs of human mast cells.(ABSTRACT TRUNCATED AT 250 WORDS)