Topic:Mast Cells
Mast cells are a type of white blood cell found in various tissues of horses, particularly in the skin, respiratory tract, and gastrointestinal system. They are involved in the body's immune response and play a significant role in allergic reactions and inflammation. Mast cells contain granules rich in histamine and other mediators that are released upon activation, contributing to the physiological processes associated with immune defense. In horses, mast cells are studied for their involvement in conditions such as allergic dermatitis, respiratory disorders, and anaphylaxis. This page compiles peer-reviewed research studies and scholarly articles that explore the distribution, function, and clinical implications of mast cells in equine health.
Evaluation of cytokine mRNA expression in bronchoalveolar lavage cells from horses with inflammatory airway disease. Inflammatory airway disease (IAD) is a common disorder of performance horses and is associated with poor performance and accumulation of mucus and inflammatory cells in lower airway secretions. Horses with IAD frequently have increased relative counts of neutrophils in bronchoalveolar lavage fluid (BALF); less commonly relative counts of eosinophils and/or mast cells may be increased. The aetiopathogenesis of IAD is unknown and may involve innate and/or acquired immune responses to various factors including respirable dust constituents, micro-organisms, noxious gases and unconditioned air. The...
RT-qPCR comparison of mast cell populations in whole blood from healthy horses and those with laminitis. Inflammatory damage to the digital laminae, a structure responsible for suspension of the distal skeleton within the hoof capsule, results in a painful and often life-threatening disease in horses called laminitis. There can be many diverse causes of laminitis; however, previous work in the horse has suggested that in each case, the inflammation and resulting tissue damage is consistent with the action of mediators released from mast cells (MC), as well as the downstream consequences of their activation. The recent development of molecular genetics tools to characterize cells based on their tr...
Kassorins: novel innate immune system peptides from skin secretions of the African hyperoliid frogs, Kassina maculata and Kassina senegalensis. From defensive skin secretions acquired from two species of African hyperoliid frogs, Kassina maculata and Kassina senegalensis, we have isolated two structurally related, C-terminally amidated tridecapeptides of novel primary structure that exhibit a broad spectrum of biological activity. In reflection of their structural novelty and species of origin, we named the peptides kassorin M (FLEGLLNTVTGLLamide; 1387.8 Da) and kassorin S (FLGGILNTITGLLamide; 1329.8 Da), respectively. The primary structure and organisation of the biosynthetic precursors of kassorins M and S were deduced from cloned s...
Large intestinal mast cell count and proteinase expression is associated with larval burden in cyathostomin-infected horses. Cyathostomins are the principal pathogenic nematode of equidae worldwide. In other species mast cell (MC) proteinases, in particular chymases, appear to have protective roles. Knowledge of the equine intestinal immune response to cyathostomins is limited. Objective: To investigate MC numbers and proteinase expression in equine cyathostomin-infected large intestine. Objective: MC populations in the large intestine are positively associated with cyathostomin burden and predominantly express chymase. Methods: The caecal cyathostomin burden of naturally infected horses (n = 25) was determined by l...
Detection of reaginic antibodies against Faenia rectivirgula from the serum of horses affected with Recurrent Airway Obstruction by an in vitro bioassay. Reaginic antibodies, mainly of the IgE and some IgG subclasses, play an important role in the induction of type I immediate hypersensitivity reactions. These antibodies bind through their Fc fragment to high affinity receptors (FcεRI) present in the membrane of mast cells and basophils. Previously, several studies have investigated the role of reaginic antibodies in the pathogenesis of RAO. However, whereas immunological aspects of RAO have been extensively studied, the precise sequence of events is still not well understood and role of IgE in this disease still remains controversial. Therefo...
Multicentric mast cell tumors in a horse. A 6-year-old female Rocky Mountain horse was presented for evaluation of draining tracts and distal limb subcutaneous edema on the left front and left hind limbs that had been present for 2 weeks. Direct smears of fluid collected by fine-needle aspiration of subcutaneous fluid from both limbs were highly cellular with a predominance of eosinophils accompanied by numerous, moderately atypical, variably granulated mast cells. The cytologic diagnosis was mast cell tumor (MCT) with prominent eosinophilic infiltration with a differential diagnosis of eosinophilic granuloma. Histologic evaluation of...
Mastocytoma in the common carpal sheath of the digital flexor tendons of a horse. A 13-year-old Morgan gelding was examined for right forelimb lameness and tenosynovitis of the right common carpal sheath of the digital flexor tendons. The horse had moderate right forelimb lameness at the trot and marked effusion of the right common carpal sheath of the digital flexor tendons. Ultrasonographic examination revealed a soft tissue mass within the proximal pouch of the affected tendon sheath, located adjacent to the distal physis of the radius. Cytology and culture of the fluid revealed a sterile, eosinophilic tenosynovitis. Tenoscopic exploration confirmed the presence of a cap...
Third eyelid resection as a treatment for suspected squamous cell carcinoma in 24 horses. Between October 2000 and January 2007, 24 horses were presented with suspected squamous cell carcinoma (SCC) of the third eyelid. The hospital's medical records were analysed retrospectively to gain data about the cases, and telephone follow-up was obtained from the owners and referring veterinary surgeons. The resected third eyelid was submitted for histological examination in 21 cases; in the other three cases the tissue was not submitted at the owners' request, for economic reasons. SCC was confirmed in 16 of these 21 cases, three cases were diagnosed histologically as lymphoid hyperplasia,...
In vitro bioassay to detect reaginic antibodies from the serum of horses affected with recurrent airway obstruction. In horses, Recurrent Airway Obstruction (RAO) is an allergic disease that involves IgE mediated Type I Hypersensitivity responses. The development of this type of allergy involves a series of events that begins with reaginic antibodies, mainly IgE and some IgG subclasses. These reaginic antibodies bind with high affinity, via the Fc portion, to FcepsilonRI receptors on the membrane of mast cells and basophils. Once bound, environmental allergens cross-link the antibodies, which results in mast cell degranulation leading to the production of histamine and other chemical mediators that act toget...
IgE in horses: occurrence in health and disease. Since the initial characterization of IgE by Ishizaka et al. (1966), IgE was described in several mammalian species. In horses, a single gene encoding the IgE heavy chain constant region (IGHE gene) exists per haploid genome and several allelic variants of the equine IGHE gene were found. IgE occurs in its soluble form in equine serum and physiological concentrations of total IgE are around 1000-fold higher in normal horse than in normal human serum. Maternal IgE is enriched in the colostrum and transferred to the neonatal foal after birth. Foals do not produce detectable concentrations of end...
Sensitization of skin mast cells with IgE antibodies to Culicoides allergens occurs frequently in clinically healthy horses. IgE antibodies are mediators of mast cell degranulation during allergic diseases. The binding of IgE to its high-affinity IgE receptor on mast cell surfaces is called "sensitization" and precedes the development of clinical allergy. Previously, intradermal injection of anti-IgE or the anti-IgG(T) antibody CVS40 induced immediate skin reactions in horses. This suggested that both IgE and IgG(T) sensitize equine skin mast cells. Here, we investigated sensitization to allergen and with IgE or IgG(T) in clinically healthy horses of different age groups. In addition, immediate skin reactions to Cul...
Maternal transfer of IgE and subsequent development of IgE responses in the horse (Equus callabus). Immunoglobulin E (IgE) mediates the immune response to parasites, but can also cause allergies. In humans maternal IgE is not transferred to cord blood and high levels of cord blood IgE are associated with subsequent allergy. In horses, both maternal IgG and IgE are transferred via colostrum; the IgE levels in the mare's serum, the colostrum and the foal's serum are correlated but the consequences of IgE transfer to foals are not known. By about 6 weeks of age the levels of IgE in foal serum have dropped to a nadir, at 6 months of age the level of IgE has risen only very slightly and is no lon...
A histamine release assay to identify sensitization to Culicoides allergens in horses with skin hypersensitivity. Skin hypersensitivity is an allergic disease induced in horses by allergens of Culicoides midges. The condition is typically diagnosed by clinical signs and in some horses in combination with allergy testing such as intradermal skin testing or serological allergen-specific IgE determination. Here, we describe an alternative method for allergy testing: a histamine release assay (HRA) that combines the functional aspects of skin testing with the convenience of submitting a blood sample. The assay is based on the principle that crosslinking of allergen-specific IgE bound via high-affinity IgE rec...
Association between cough and cytology of bronchoalveolar lavage fluid and pulmonary function in horses diagnosed with inflammatory airway disease. The objective of this study was to examine the relationship between chronic cough, pulmonary mechanical function, bronchial hyper-responsiveness, and peripheral airway inflammation in adult performance horses with nonseptic inflammatory airway disease (IAD). Objective: We hypothesized that horses with a presenting complaint of cough have a higher percentage of inflammatory cells on bronchoalveolar lavage (BAL), greater airway obstruction, and airway hyper-responsiveness (AHR) than do horses without cough. ANIMALS/SAMPLE POPULATION: Adult performance horses (n = 137) referred for evaluation of ...
Comparison of cellular and humoral immunoassays for the assessment of summer eczema in horses. The objective of this study was to compare and analyze three common diagnostic methods for summer eczema (SE) in horses, an allergic dermatitis caused by bites of Culicoides spp. Nine horses with a medical history of SE and nine control animals were intradermally challenged with whole body extracts (WBE) and the saliva of a native (C. nubeculosus) and exotic (C. sonorensis) Culicoides species. Blood and serum samples of the horses were examined for basophil reactivity by a histamine release test (HRT) and for Culicoides-specific serum immunoglobulin E (IgE) and G (IgG) by enzyme-linked immunos...
Organic dust exposure increases mast cell tryptase in bronchoalveolar lavage fluid and airway epithelium of heaves horses. Mast cell degranulation is believed to act as a key event in initiating and maintaining airway response to allergen challenge in human asthma. It is hypothesized that the mast cell may play a similar role in equine heaves, which shares many similarities with occupational dust-induced asthma. Objective: The aim of this study was to quantify the mast cell proteinase tryptase in bronchoalveolar lavage fluid (BALF) from control and heaves-susceptible horses and to investigate tryptase mRNA and protein expression in pulmonary mast cells. Methods: Equine BALF tryptase concentrations were determined ...
A subcutaneous mass on the neck of a horse. A 25-year-old Arabian gelding was presented for investigation of a subcutaneous neck mass. Fine-needle aspirates and impression smears revealed mast cells with widely varying degrees of cytoplasmic granulation and scattered eosinophils. Histopathology revealed a poorly circumscribed mass composed of sheets and bundles of mast cells with a large population of eosinophils. The mast cells were separated into numerous lobules by a heavy collagenous stroma, and multifocal collagen necrosis was present. Strong reactivity of the tumor cells for both Giemsa and toluidine blue stains confirmed the diag...
Cellular basis of chronic obstructive pulmonary disease in horses. Chronic obstructive pulmonary disease (COPD) is an inflammatory obstructive disease of the airways characterized with hypersensitivity of the airway tissues to various allergens, most commonly the fungi contained in the poor-quality hay and straw bedding-Saccharopolyspora rectivirgula, Aspergillus fumigatus, and Thermoactinomyces vulgaris. It is manifested clinically in middle-aged horses with recurrent episodes of dyspnea, chronic cough, and their reduced athletic and working capacity. Pulmonary emphysema and lack of pulmonary collapse are the most common gross lesion. Pathohistological findi...
Imaging diagnosis–equine mast cell tumor. Equine mast cell tumors are typically benign solitary growths of the head, neck, trunk, or limbs. When involving the limbs, these masses tend to be adjacent to joints without involving them. In radiographs there is often a well-circumscribed soft tissue mass with granular mineralization. The Arabian breed appears to be over represented. Surgical removal is usually curative. In this report, we describe the diagnosis, clinical features, and management of mast cell tumors in the rear limb of a horse.
Lactoferrin, a glycoprotein with immunomodulatory and mast cell stabilising properties, in skin of horses suffering from Culicoides hypersensitivity. Lactoferrin (LF), a glycogen of the transferrin family with anti-bacterial and immunomodulatory properties, is expressed in various secretions and tissues. Cutaneous LF serves as a mast cell stabilising compound, modulates T cell activity and is found during IgE-mediated late phase reactions at allergen challenged sites. Culicoides hypersensitivity (CHS) in horses is a common IgE-mediated allergic dermatitis, characterised by an early and late phase cutaneous reaction upon allergen challenge. The aim of the study presented here was to examine whether LF mRNA expression in skin biopsies from ho...
Early onset airway obstruction in response to organic dust in the horse. Equine recurrent airway obstruction (RAO) has been used as a naturally occurring model of human asthma. However, it is unknown whether there is an early-phase response in RAO. The aim of this study was to determine whether exposure to organic dust induces immediate changes in lung function in RAO-affected horses, which could be mediated by airway mast cells. Six RAO-affected horses in remission and six control horses were challenged with hay-straw dust suspension by nebulization. Total respiratory resistance at 1 Hz, measured by forced oscillation, was increased from 0.62 +/- 0.09 cmH(2)O.l(-1...
The involvement of mast cells and mast cell proteinases in the intestinal response to equine cyathostomin infection. Cyathostomins (Cyathostominae) are regarded as the most pathogenic equine nematode worldwide. These nematodes are difficult to control in equine populations due to emerging anthelmintic resistance and evasion of encysted larval cyathostomins to regular modern anthelmintics. Mast cells and their proteinases have been shown to play a role in the mammalian immune response to nematode infections. Involvement of mast cells and mast cell proteinases in the equine immune response to cyathostomin infection is proposed. A technique was established to perform immunohistochemical staining using polyclona...
cDNA cloning and substrate specificity of equine tryptase, a possible mediator in equine heaves. Mast cell mediators are believed to play a central role in inflammatory lung disorders such as human allergic and occupational asthma. Equine heaves is characterized by reversible neutrophilic airway inflammation and airway obstruction, primarily due to bronchospasm and mucus hypersecretion, following exposure of susceptible horses to organic stable dusts. As such, heaves shares many similarities with human occupational dust-induced asthma and therefore it is proposed that mast cells may also be implicated in the pathogenesis of heaves. Tryptase, a mast cell-specific proteinase, can be used as...
Distribution of CCR3 mRNA expression in horse tissues. CCL11 (also known as eotaxin) is a very potent and selective mediator of eosinophil migration which exerts its effects through its receptor, CCR3. In this study we report the cloning of an equine CCR3 cDNA sequence and investigation of the localization of CCR3 mRNA expression in horse tissues. Equine CCR3 displayed high levels of sequence identity with CCR3 sequences in other species. RT-PCR analysis revealed the expression of CCR3 in colon, lung and spleen of normal horses. In situ hybridisation experiments indicated that expression of CCR3 mRNA in colon was predominantly in eosinophils and t...
IgE and IgG antibodies in skin allergy of the horse. In horses, allergies have been characterized by clinical signs and/or intradermal (i.d.) allergen testing. Our aim was to find the first direct evidence that immunoglobulin E (IgE) mediates equine allergy. In addition, we tested the hypothesis that immediate skin reactions in horses can also be mediated by IgG. Anti-IgE affinity columns were used to purify IgE from serum of one healthy horse and three horses affected with summer eczema, an allergic dermatitis which is believed to be induced by Culicoides midges. A modified Prausnitz-Küstner experiment was performed in four clinical healthy ho...
Comparison of four staining methods for detection of mast cells in equine bronchoalveolar lavage fluid. Mast cells normally are present in equine bronchoalveolar lavage fluid (BALF), but usually represent <2% of all cells in healthy horses. An increased percentage of mast cells has been associated with airway hyperactivity and inflammatory airway diseases, but marked differences are reported between studies in normal and diseased horses. Because an abnormal mast cell count may be of clinical relevance, we compared the ability of a fast Romanowsky method to stain mast cell granules with that of 3 metachromatic stains: automated Romanowsky, May-Grünwald Giemsa, and toluidine blue stains. The B...
Production of monoclonal antibodies specific for native equine IgE and their application to monitor total serum IgE responses in Icelandic and non-Icelandic horses with insect bite dermal hypersensitivity. Immunoglobulin E forms a minor component of serum antibody in mammals. In tissues IgE is bound by FcvarepsilonRI receptors on the surface of mast cells and mediates their release of inflammatory substances in response to antigen. IgE and mast cells have a central role in immunity to parasites and the pathogenesis of allergic diseases in horses and other mammals. This paper describes the production of several novel monoclonal antibodies that detect native equine IgE in immunohistology, ELISA and Western blotting. An antigen capture ELISA to quantify equine IgE in serum has been developed using ...
Occurrence of IgE in foals: evidence for transfer of maternal IgE by the colostrum and late onset of endogenous IgE production in the horse. IgE is the key antibody involved in type I allergies. Allergen mediated crosslinking of IgE bound to high affinity Fcepsilon-receptors on mast cells and basophils stimulates cellular degranulation and release of inflammatory mediators and cytokines. In this report, we demonstrate that IgE antibodies can be transferred from the mother to offspring in horses via the colostrum. We found a clear correlation between the IgE concentration in colostrum and the total IgE concentration in foal sera on day 2 after birth (r(sp)=0.83). Maternal IgE was detected in foal sera by ELISA and on peripheral bloo...