Leukocytes, also known as white blood cells, are an integral component of the equine immune system, responsible for defending horses against infections and foreign substances. These cells are produced in the bone marrow and circulate throughout the bloodstream and tissues. In horses, leukocytes are categorized into several types, including neutrophils, lymphocytes, monocytes, eosinophils, and basophils, each with specific functions in immune response. Neutrophils are involved in phagocytosis and the destruction of pathogens, while lymphocytes are key players in adaptive immunity. Monocytes differentiate into macrophages and dendritic cells, contributing to pathogen clearance and antigen presentation. Eosinophils and basophils are associated with allergic reactions and parasitic infections. Variations in leukocyte counts and distribution can indicate underlying health conditions, making them valuable in veterinary diagnostics. This page aggregates peer-reviewed research studies and scholarly articles that explore the physiology, function, and diagnostic relevance of leukocytes in equine health.
Wagner B, Radbruch A, Rohwer J, Leibold W.In this study we describe the generation of monoclonal antibodies (mAbs), which recognize different epitopes of the equine IgE constant heavy chain. Equi-murine recombinant IgE (rIgE), composed of the murine V(H)186.2 heavy chain variable region, linked to the equine IgE constant heavy chain and expressed together with the murine lambda(1) chain in J558L cells was used to immunize BALB/C mice. A total of 17 different mAbs were obtained, which recognized the rIgE heavy chain constant region. None of the mAbs reacted with monoclonal equine isotypes IgM, IgG1 (IgGa), IgG3 (IgG(T)), IgG4 (IgGb) or...
Jefcoat AM, Wagner JG, Robinson NE.The research article involves an in-depth exploration of the role of neutrophils, a type of immune cell, in inflammation, especially in relation to horse diseases. The study discusses the historical […]
Lalko CC, Deppe E, Ulatowski D, Lutgen A, Hart AP, Patton EA, Lunn DP, Suresh M, Darien BJ.Acute inflammatory diseases, such as colic, septicemia and endotoxemia are common in equines and have been shown to be correlated to vascular injury and thrombosis. In humans with similar thrombotic conditions, P-selectin and P-selectin glycoprotein ligand-1 (PSGL-1)-mediated platelet-leukocyte adhesion contributes to the pathogenesis of these disorders through the generation of inflammatory mediators and tissue factor. As such, we hypothesized that a P-selectin-PSGL-1 (platelet-leukocyte) interaction, similar to that in humans, may also exist in the horse. The objective of this study was to i...
Lees P, Landoni MF.Carprofen is a nonsteroidal anti-inflammatory drug of the 2-arylpropionate subclass. It contains a single chiral centre and exists in two enantiomeric forms. In this study rac-carprofen, at two dosages, 0.7 and 4.0 mg/kg, and placebo were administered i.v. to six New Forest horses in a three period cross-over study. The concentration-time profiles were established for R(-) and S(+)-carprofen for plasma and both inflamed (exudate) and noninflamed (transudate) tissue cage fluids. R(-)-carprofen was the predominant enantiomer in all three fluids, as indicated by plasma area under the curve (AUC) ...
Hultén C, Demmers S.Differentiation between infectious and noninfectious disease and rapid initiation of accurate treatment are essential in managing diseases in the neonatal and young foal. Identification of useful inflammatory markers for these purposes is, therefore, of great importance. The aim of this study was to compare the responses of the acute phase protein serum amyloid A (SAA) with the responses of fibrinogen and total leucocyte and neutrophil counts in infectious diseases encountered in the young foal, and to assess whether SAA measurements give additional information useful in the management of thes...
Wagner B, Siebenkotten G, Leibold W, Radbruch A.Due to characteristic clinical signs, immunoglobulins of isotype E (IgE) are believed to be involved in several allergic diseases of the horse. To date, closer investigations have been hampered by the fact that neither purified equine IgE nor anti-equine IgE monoclonal antibodies were available for IgE isotype determination. As an approach to solve this problem, we constructed a stable cell line (EqE6) that expresses recombinant equi-murine IgE specific for 4-(hydroxy-3-nitro-phenyl) acetyl (NP). Biochemical analysis of the purified protein revealed a highly glycosilated IgE monomer of approxi...
Colahan PT, Kollias-Bakert C, Leutenegger CM, Jones JH.Physical exertion is a stimulus for the upregulation of cytokine production including IL-1beta, IL-1ra, IL-2, IL-4, IL-6, IL-10 and TNF-alpha in horses. To investigate that hypothesis, we initiated training of 5 stall-rested Thoroughbreds. Blood samples were drawn before and weekly during training. The relative transcription of mRNA within the leucocytes was measured using real time TaqMan quantitative PCR. The training protocol was walking (3 min), trotting (3 min) and cantering/galloping (6 min) increasing in intensity weekly (6 to 12 m/s) and culminating in an intense exercise period. Compa...
Winchell WW, Hardy J, Levine DM, Parker TS, Gordon BR, Saal SD.To evaluate the effect of a phospholipid emulsion (PLE) on the initial response of horses to administration of endotoxin. Methods: 12 healthy adult horses. Methods: Horses were assigned to 2 treatment groups (6 horses/group). The control group was administered 1 L of saline (0.9% NaCl) solution, and the treated group was administered PLE (200 mg/kg, IV); treatments were administered during a period of 120 minutes. An infusion of endotoxin was initiated in both groups starting 1 hour after initiation of the saline or PLE solutions. Physical examination and hemodynamic variables were recorded, a...
Zizzadoro C, Belloli C, Badino P, Ormas P.A method for the separation of pure and viable lymphocytes and granulocytes from the same blood sample in horses was reported. By centrifuging equine heparinized blood at 100 xg for 10 min at room temperature (r.t.), the resulting supernatant plasma was an almost pure (97.71 +/- 0.30%; n = 15) suspension of highly viable (98.72 +/- 0.28%) lymphocytes. When sodium citrate was used as an anticoagulant, lymphocyte suspensions collected in the same manner showed lower purity (87.89 +/- 1.59%; n = 9) and higher yields (56.56 +/- 3.89%, n = 9 versus 36.11 +/- 2.23%, n = 15). Where needed, a further ...
Kim HY, Mott J, Zhi N, Tajima T, Rikihisa Y.Human granulocytic ehrlichiosis (HGE), a tick-borne zoonosis, is caused by an obligatory intragranulocytic bacterium, the HGE agent, a strain of Anaplasma phagocytophila. The equine model of HGE is considered valuable in understanding pathogenic and immune mechanisms of HGE. In the present study, cytokine mRNA expression by peripheral blood leukocytes (PBLs) in horses was examined during the course of infection by intravenous inoculation of A. phagocytophila or by allowing feeding by infected ticks. The p44 genes encoding the major outer membrane protein P44s of A. phagocytophila were detected...
Smith D, Hamblin A, Edington N.Antisera to activated equine endothelial cells, which detected surface molecules of 116 kD, 97 kD, 42 kD and 38 kD, were made to investigate the role of endothelial adhesion molecules in equid herpes virus 1 infection. These putative adhesion molecules could be induced by 17-beta oestradiol, chorionic gonadotrophin, or IL-2, as well as by LPS and PWM. In an in vitro flow system, using equine veins or arteries, equid herpesvirus 1 in leucocytes was only transferred to infect endothelial cells if both leucocytes and endothelial cells expressed these surface molecules. Blocking of the membrane mo...
Gilger BC, Yang P, Salmon JH, Jaffe GJ, Allen JB.To determine whether a chemokine (RANTES)-like protein expressed by ciliary epithelium plays a role in uveitis. Methods: 3 clinically normal horses intradermal, 5 eyes from 5 horses with recurrent uveitis, and 10 normal eyes from 5 age- and sex-matched horses. Methods: Cross-reactivity and sensitivity of recombinant human (rh)-regulated upon activation, normal T-cell expressed and secreted (RANTES) protein were evaluated in horses by use of intradermal hypersensitivity reactions and a chemotaxis assay. Aqueous humor and ciliary body of eyes from clinically normal horses and horses with uveitis...
O'Neill W, McKee S, Clarke AF.This study was undertaken to compile new data on the efficacy of Echinacea in stimulating the immune system of the horse. Use of Echinacea is becoming widespread in horses, despite an absence of controlled laboratory research into its effectiveness or safety. This paper documents results of a double-blind, placebo-controlled, cross-over trial investigating the effect of standardised Echinacea extract on 8 horses. Animals were supplemented with Echinacea or placebo for 42 days, and their response to supplements recorded. Treatment with Echinacea increased phagocytic ability of isolated neutroph...
Lawler DF, Brazil TJ, Dagleish MP, Watson ED.This study investigated the chemotactic activity of equine CL at different stages of the oestrous cycle. The purpose of this was to ascertain whether luteal tissue itself contributes to the massive influx of leucocytes around the time of natural and induced luteal regression. Corpora lutea were collected at different stages of dioestrus and after treatment with PGF2alpha. Culture medium harvested after incubation of luteal tissue for 20 h was chemotactic for both polymorphonuclear and mononuclear cells in late dioestrus (before functional regression) as well as after natural and induced luteal...
Arai T, Hosoya M, Nakamura M, Magoori E, Uematsu Y, Sako T.The activities of the enzymes involved in the malate-aspartate shuttle and m RNA expression of malate dehydrogenase (MDH), a crucial enzyme for the NADH shuttle that produces ATP in glucose metabolism in the peripheral leukocytes of horses, were measured to investigate the change in metabolic states with training. There were no significant differences in plasma glucose and immunoreactive insulin concentrations between race horses and riding horses, used as a comparable reference. The cytosolic and mitochondrial MDH activities in leukocytes of race horses were significantly higher than those of...
Allen AL, Myers SL, Searcy GP, Fretz PB.The Hematologic values of 19 equine fetuses between 202 and 238 days gestation were compared with those of their dams. The red blood cell (RBC) count, hemoglobin concentration, hematocrit, and mean corpuscular hemoglobin concentration were significantly lower in fetal blood, while the mean corpuscular volume, mean corpuscular hemoglobin, and red cell distribution width were significantly higher. Mares had a significantly higher nucleated blood cell count than fetuses, and all nucleated cells were leukocytes (WBC). Most WBC in mare blood were segmented neutrophils and lymphocytes. In contrast, ...
Lindberg A, Näsman-Glaser B, Lindgren JA, Robinson NE.To evaluate leukotriene (LT) biosynthetic capacity in lung tissue from healthy horses and horses with recurrent airway obstruction (RAO). Methods: Lung parenchyma and airway specimens from 8 RAO-affected and 5 healthy horses. Methods: Horses were stabled for > or = 72 hours. Blood was drawn before euthanasia, after which lung specimens were collected. Tissue strips from small airways and parenchyma were incubated in organ baths with the precursor LTA4 or stimulated with calcium ionophore A23187 or the tripeptide N-formyl-Met-Leu-Phe (fMLP), with or without exogenous arachidonic acid, in the...
Baumber J, Vo A, Sabeur K, Ball BA.Contaminating leukocytes in the ejaculate are an important source of reactive oxygen species (ROS) in human semen. When present in sufficient numbers, they can have a detrimental influence on sperm function in humans. Unfortunately, there is little published information regarding the importance of leukocytes in stallion semen. The objectives of this study were to determine the production of hydrogen peroxide (H2O2) by activated equine neutrophils and to examine the effect of this ROS production on equine sperm motility in vitro. Motile equine spermatozoa (two ejaculates each from four stallion...
Baker JM, Stidworthy M, Gull T, Novak J, Miller JM, Antczak DF.Serological and cellular assays and molecular techniques were used to define features of the major histocompatibility complex (MHC) of the donkey With this information in hand, immune recognition of MHC determinants within and between donkeys and horses was compared. An antibody-mediated, complement-dependent, microcytotoxicity assay using a variety of antisera to donkey histocompatibility antigens, including those induced as a result of intraspecies or interspecies pregnancy in horse mares and jenny donkeys, delineated five donkey leukocyte antigen (DoLA) specificities. Antisera raised across...
Smith R, Chaffin MK, Cohen ND, Martens RJ.To characterize changes in lymphocyte subsets over time in foals from birth to 18 weeks of age, accounting for differences among individuals, and to determine the effect of overnight storage of blood samples on foal lymphocyte subset concentrations. Methods: 8 healthy Quarter Horse foals from birth to 18 weeks of age. Methods: Blood samples were collected longitudinally from birth to 18 weeks of age and a CBC performed on each sample. The samples were stained for lymphocyte markers, either immediately or after overnight storage and analyzed by flow cytometry. Results: Total leukocytes, total l...
Flaminio MJ, Rush BR, Davis EG, Hennessy K, Shuman W, Wilkerson MJ.This paper describes a method for simultaneously measuring phagocytosis and oxidative burst activity in equine peripheral blood leukocytes by flow cytometry. Opsonized propidium iodide-labelled Staphylococcus aureus (PI-Sa) was used to measure the uptake of bacteria by equine phacocytes and the oxidative burst activity by oxidation of dihydrorhodamine 123. The requirements to achieve optimal activity of phagocytosis and oxidative burst are described. The advantage of the simultaneous technique is that it provides both independent and comparative values for phagocytosis and the oxidative burst,...
Macintyre AR, Dixon JB.To determine whether living hydatid tissue can, like hydatid fluid, regulate leukocyte growth, T-cell, B-cell, and macrophage lines were cocultured with protoscoleces of Echinococcus granulosus and their growth was compared with that of control cultures by thymidine uptake estimates and chemiluminescent assays of cell number. Protoscoleces supported mitosis of IL-1-deprived D10 T cells, but did not increase D10 count. The action of protoscoleces was affected by the species and organ of their origin and the length of time in culture. Unusually marked mitotic reaction, unaffected by parasite age...
Marr KA, Lees P, Cunningham FM.Activation of circulating neutrophils has been observed following challenge of horses with chronic obstructive pulmonary disease (COPD) and may facilitate the accumulation of these cells in the airways. In this study, no significant difference was observed between adherence to protein coated plastic of blood neutrophils from asymptomatic COPD-susceptible and normal horses stimulated by the mediators PAF, human recombinant (hr)IL-8 and hrC5a. Twenty-four hours after the start of a 7 h antigen challenge, adherence of unstimulated neutrophils from COPD-susceptible horses increased from 2.5 (0.5-4...
Bell SC, Savidge C, Taylor P, Knottenbelt DC, Carter SD.A putative immunodeficiency, causing mortality in UK Fell pony foals (Fell pony syndrome), was studied in affected foals and compared with healthy, age-matched foals. Differential cell counts of peripheral blood indicated that the syndrome foals were lymphopenic (P<0.05). Flow cytometric analysis of circulating leucocytes showed a reduced MHC II expression (P<0.01) on lymphocytes but not on polymorphonuclear cells in affected foals. There were no changes in the percentages of CD4+ or CD8+ T cells. There was an increased (P<0.05) expression of CD11a/18 by the lymphocytes of the syndrom...
Demmers S, Johannisson A, Gröndahl G, Jensen-Waern M.The aim of this study was to investigate the phagocytic and killing capacities as well as expression of CD18 of neutrophils obtained from healthy foals from birth to age 8 months. Blood was taken from 6 Standardbred foals at 7 time-points between ages 2-56 days and thereafter once a month. For comparison, cells from 16 mature horses were evaluated. Neutrophil phagocytosis of yeast cells was assessed by flow cytometry after opsonisation with mature pooled serum, autologous serum or anti-yeast IgG. The killing capacity of the neutrophils, as indicated by the oxidative burst, was monitored by che...
Katila T.The uterus of domestic animals, including the horse, has a dual role in the interaction of the uterus and sperm. On one hand, uterine contractions carry sperm toward the oviduct, and on the other hand the uterus eliminates excessive sperm. The selection of sperm for the small numbers of "good" cells that gain access to the oviduct and for the majority of sperm that will be destroyed takes place in the uterus. The sperm-uterine interaction works both ways; sperm and seminal plasma also have several effects on the uterus. Sperm and seminal plasma probably provoke uterine contractions. Sperm indu...
Horohov DW, Kydd JH, Hannant D.Horses greater than 20 years of age exhibit alterations in their immune responses similar to those observed in other aged individuals. The purpose of this study was to characterize immunosenescence in a population of aged ponies. The peripheral blood mononuclear cells (PBMC) from aged ponies exhibited a decreased proliferative response to various mitogens that was not overcome by the addition of interleukin 2 (IL-2) to the cultures. No difference in overall expression of the IL-2 receptor was seen between young and aged ponies, though CD8(+) cells from aged ponies exhibited increased levels of...
Kershaw O, von Oppen T, Glitz F, Deegen E, Ludwig H, Borchers K.The prevalence of EHV-2 in 27 horses with keratoconjunctivitis and 21 clinically healthy horses of different ages and stocks were analyzed. We demonstrated that EHV-2 was present in 12 keratoconjunctivitis cases as shown by nested PCR on ocular swabs. This is statistically more often than in the control group, where only two ocular swabs were EHV-2 positive. Cocultivation was successful on peripheral blood leukocytes of healthy and diseased horses but not on swabs. We isolated ten EHV-2 strains from diseased and nine from control horses, whereas 16 isolates showed different restriction enzyme ...
Hedges JF, Demaula CD, Moore BD, McLaughlin BE, Simon SI, MacLachlan NJ.Expression of E-selectin on activated endothelium is a critical initial step that leads to extravasation of leucocytes during inflammation, yet E-selectin is largely uncharacterized in several animal species including the horse. We have sequenced and compared E-selectin genes derived from activated cultures of purified equine (horse), cervid (black-tailed deer) and ovine (sheep) pulmonary artery endothelial cells (ECs). Phylogenetic and amino acid sequence comparisons indicate that bovine, cervid and ovine E-selectin are similar, whereas human and equine E-selectin are more closely related to ...
Lumsden JH, Valli VE, McSherry BJ, Robinson GA, Claxton MJ.Hemorrhagic anemia was experimentally produced in three Standardbred horses by removing approximately 63% of the red cell mass and the accompanying plasma during a three day interval. Red cell parameters were examined daily for 45 days and then weekly until termination of the experiment 250 days after production of the anemia. Leukocytes, platelets and bone marrow aspirates were examined at regular intervals for 25 days after the final phlebotomy. At 24 hours after the last bleeding, 75-selenomethionine was injected intravenously to measure the lifespan of the newly produced erythrocytes. The ...
Denham J, Stevenson K, Denham MM.Telomeres are genetically conserved repetitive terminal DNA that protect against genomic instability and shorten with ageing. Here, we reveal the leukocyte telomere length of Equus caballus by measuring terminal restriction fragments (TRFs) using Southern Blot analysis in a cohort of 43 Thoroughbred horses (age: 24 h-25 years). Heterogeneous TRFs were observed in each animal and large inter-animal variation in mean TRF was observed (range: 10.5-18.7 kbp). Mean TRFs were inversely correlated with age (r = -0.47). The estimated yearly rate of telomere attrition was 134 bp. Horses shoul...
Valdez SC, Nieto JE, Spier SJ, Owens SD, Beldomenico P, Snyder JR.To determine the effects of an external nasal dilator strip on cytologic characteristics of bronchoalveolar lavage (BAL) fluid in racing Thoroughbreds. Methods: Clinical trial. Methods: 23 Thoroughbred racehorses in active training. Methods: Each horse raced on 2 occasions: once while wearing an external nasal dilator strip and once while not. Bronchoalveolar lavage was performed 12 to 18 hours after each race, and BAL fluid was analyzed for RBC and leukocyte counts and hemosiderin content. Results: Mean +/- SEM count of RBCs in BAL fluid when horses raced without the nasal dilator strip (84.6...
Wilks CR.The immune response in horses following experimental infection with equine herpesvirus type 1 (EHV-1) was assessed by measuring cytotoxicity for EHV-1-infected target cells. A technique was developed, using [125I]5-iodo-2'-deoxyuridine ([125I]IUDR)-labeled equine fetal kidney cells infected with EHV-1 as the target cells. It was shown that peripheral blood leukocytes from a recovered horse were capable of lysing target cells, as measured by the loss of radio-active label. Following the experimental infection of specific-pathogen-free ponies with EHV-1, cytotoxicity was obtained with fresh auto...
Winchell WW, Hardy J, Levine DM, Parker TS, Gordon BR, Saal SD.To evaluate the effect of a phospholipid emulsion (PLE) on the initial response of horses to administration of endotoxin. Methods: 12 healthy adult horses. Methods: Horses were assigned to 2 treatment groups (6 horses/group). The control group was administered 1 L of saline (0.9% NaCl) solution, and the treated group was administered PLE (200 mg/kg, IV); treatments were administered during a period of 120 minutes. An infusion of endotoxin was initiated in both groups starting 1 hour after initiation of the saline or PLE solutions. Physical examination and hemodynamic variables were recorded, a...
Kobayashi A, Sugisaka M, Takehana K, Yamaguchi M, Eerdunchaolu , Iwasa EK, Abe M.This report compares the morphology and the concentrations of glycos-aminoglycans (GAGs) in an injured superficial digital flexor tendon (SDFT) of a horse with those of a normal tendon. An injured 6-year-old male Thoroughbred exhibited heat and swelling around the SDFT of the right forelimb. On histopathological examination, exuberant granulation was observed in the affected tendon, with activated tenocytes, angiogenesis, haemorrhage, and infiltration of small numbers of leucocytes. The collagen fibres were loosely packed and irregularly arranged. The diameter of control collagen fibrils was 2...
Banks KL, Greenlee A.Various cell populations of equine mononuclear leukocytes were identified and isolated. Mononuclear leukocytes were concentrated by isopyknic centrifugation, using a solution of Ficoll and Hypaque. Three additional techniques were explored to separate monocytes from lymphocytes, and 3 methods were used to separate lymphocyte types. Cytochemical techniques for the detection of nonspecific esterase readily distinguished equine monocytes from lymphocytes. Peripheral blood lymphocytes were separated into at least 2 populations. One population had surface traits identical to thymocytes [ie, they re...
Froscher BG, Nagode LA.Alkaline phosphatase isoenzymes from small intestine, cecum, large colon, small colon, liver, kidney, leukocytes, and serum from ten clinically normal horses were defined by their sensitivities to L-phenylalanine, L-homoarginine, levamisole and heat, and by polyacrylamide gel disc electrophoresis. Readily identifiable isoenzymes occurred in small intestine, granulocytes, kidney, cecum, and large and small colon. By contrast, alkaline phosphatases from liver, lymphocytes, and serum could not be discriminated by this group of tests.
Ringger NC, Edens L, Bain P, Raskin RE, Larock R.A 5-year-old Thoroughbred mare presented with a 4 week history of weight loss, fever and leukopenia. Rectally, a large active foetus, thickened spleen and an abdominal mass were palpated. Leukopenia, mild anaemia, marked thrombocytopenia and hyperfibrinogenaemia were found. Cytology and cytochemical staining of a bone marrow aspirate supported a diagnosis of acute myelogenous leukaemia. The mare deteriorated despite medical therapy and was humanely euthanased.
Forbes G, Feary DJ, Savage CJ, Nath L, Church S, Lording P.A 10-week-old Thoroughbred filly was referred for anaemia of 4 weeks' duration. Haematology revealed severe anaemia and panleucopenia. Cytological examination of bone marrow smears revealed a myeloid to erythroid ratio <0.02:1 (reference range 0.5-2.4:1.0) and an abundance of erythroid precursor cells. The erythroid cell population included rubriblasts, prorubricytes and rubricytes, with only scant numbers of metarubricytes present. There were numerous mitotic erythroid cells, some of which were atypical and megaloblastic. These cytomorphological changes are consistent with pure acute eryth...
Lunn DP, Hurley DJ.The underlying pathogenesis of laminitis clearly depends importantly on inflammatory processes that recruit leukocytes at an early stage in disease. The role of leukocytes in the initiation of laminitis, or as an intermediary factor is currently being investigated using a limited array of models, and future studies require both new reagent and model systems if we are to clearly define how leukocytes propagate this disease. The opportunities presented by this type of research could easily include new and powerful treatment and preventative modalities.
Furr MO, Crisman MV, Robertson J, Barta O, Swecker WS.Immune system dysfunction and immunoglobulin deficiency was diagnosed in a 2-year-old horse with disseminated lymphosarcoma. Prolonged (35 days) parenteral nutrition was delivered to support the horse during a period in which immune function studies could be performed. Correction of nutritional compromise by use of parenteral nutrition did not correct the immunoglobulin deficiency, and results of lymphocyte phenotype testing did not indicate abnormal proportions of leukocytes. Lymphoblast transformation studies were suggestive of a circulating immunosuppressive factor in the horse's serum. Nor...
Kiku Y, Kusano K, Miyake H, Fukuda S, Takahashi J, Inotsume M, Hirano S, Yoshihara T, Toribio RE, Okada H, Yoshino TO.Cellular activation and functional cell surface markers were evaluated during experimentally-induced endotoxemia in healthy horses. Eight healthy adult horses were infused a low dose of endotoxin (lipopolysaccharide from Escherichia coli O26: B6, 30 ng/kg of body weight, IV) and five control horses were given an equivalent volume of sterile saline solution. Venous blood samples were collected for flow cytometric analysis of peripheral blood mononuclear cells (PBMCs) and to measure plasma endotoxin concentrations. Clinical signs of endotoxemia were recorded at 10, 20, 30, 40, 50 min, 1, 2, 3, 4...
Floyd K, Suter PF, Lutz H.Direct staining of the granules of blood eosinophils by anti-immunoglobulin fluorescein isothiocyanate (FITC) conjugates was observed when feline blood smears were tested for presence of feline leukemia virus (FeLV) antigen by immunofluorescent antibody. When blood smears of other species including swine, horses, cattle, dogs, sheep, birds, and human beings were examined, direct staining of eosinophils by FITC conjugates was also detected. This FITC staining was restricted to eosinophils and was not observed in neutrophils, lymphocytes, and platelets. Direct FITC staining of eosinophils does n...
Foster AP, Cunningham FM.The tachykinin, substance P (SP), affects eosinophil function by direct and indirect mechanisms and has been shown to cause equine eosinophils to adhere to vascular endothelium and to release cytokines that increase cell adherence. The aim of this study was to determine whether SP could act directly on equine eosinophils in vitro. Eosinophil activation was also compared in cells from normal ponies and those with insect hypersensitivity as SP may be released in the skin of hypersensitive animals. SP caused equine eosinophils to adhere, migrate and produce superoxide, although high concentration...
Mäkinen PE, Archer DC, Baptiste KE, Malbon A, Proudman CJ, Kipar A.Idiopathic focal eosinophilic enteritis (IFEE) and diffuse eosinophilic enteritis (DEE) are primary eosinophilic intestinal conditions without a known cause that are associated with an increasing number of surgical colic cases. Histology may be helpful in defining disease aetiology and pathogenesis. Objective: To characterise further the inflammatory infiltrate in equine IFEE and to compare the condition with DEE. Methods: Twenty-three IFEE cases and 5 DEE cases were examined by light microscopy including immunohistology to identify infiltrating leucocytes. Inflammatory infiltrates in mucosa a...
Wilson DG, Cooley AJ, MacWilliams PS, Markel MD.In six horses, a 0.05% solution of chlorhexidine diacetate was used to lavage one tarsocrural joint; the contralateral control joint was lavaged with lactated Ringer's solution. Horses were evaluated daily for lameness. Synovial fluid samples were collected on days 1, 4, and 8 for determination of protein concentration, total and differential leukocyte counts, and mucin clot formation. After death on day 8, synovium and osteochondral samples were collected from the tarsocrural joints for examination of morphology and proteoglycan staining. Lavage with chlorhexidine solution caused lameness tha...
Ellis JA, Steeves E, Wright AK, Bogdan JR, Davis WC, Kanara EW, Haines DM.The objective of this study was to determine whether the administration of modified-live equine herpesvirus (EHV-1) to young horses with residual maternal antibodies stimulated EHV-specific cytolytic responses, and whether these responses were crossreactive between EHV-1 and EHV-4. Eighteen clinically normal Belgian cross-foals were used in the study and were commingled in two adjacent pens. Skin biopsies were harvested from 16 foals within 24 h of birth and fibroblast cultures were established, expanded and cryopreserved. Beginning at approximately 10 weeks of age, 10 randomly chosen foals we...
Lalko CC, Deppe E, Ulatowski D, Lutgen A, Hart AP, Patton EA, Lunn DP, Suresh M, Darien BJ.Acute inflammatory diseases, such as colic, septicemia and endotoxemia are common in equines and have been shown to be correlated to vascular injury and thrombosis. In humans with similar thrombotic conditions, P-selectin and P-selectin glycoprotein ligand-1 (PSGL-1)-mediated platelet-leukocyte adhesion contributes to the pathogenesis of these disorders through the generation of inflammatory mediators and tissue factor. As such, we hypothesized that a P-selectin-PSGL-1 (platelet-leukocyte) interaction, similar to that in humans, may also exist in the horse. The objective of this study was to i...
Bumgardner MK, Dutta SK, Campbell DL, Myrup AC.Six pony foals, free of detectable serum neutralization (SN) antibody against equine herpesvirus type 1 by the standard virus-neutralization (VN) test, were inoculated with equine herpesvirus type 1. The ponies showed typical clinical signs of respiratory tract disease and developed a transient leukopenia, involving lymphocytes as well as neutrophils. The leukopenia reached its lowest point on postinoculation days (PID) 3 to 5 and then returned to base-line values by PID 8 to 10. On quantitation of lymphocyte subpopulations, T and B lymphocytes were decreased during the onset of leukopenia and...
Lees P, May SA, Hoeijmakers M, Coert A, Rens PV.The pharmacodynamics and enantioselective pharmacokinetics of vedaprofen were studied in six ponies in a two period cross-over study, in which a mild acute inflammatory reaction was induced by carrageenan soaked sponges implanted subcutaneously in the neck. Vedaprofen, administered intravenously at a dosage of 1 mg/kg, produced significant and prolonged inhibition of ex vivo serum thromboxane B2 (TXB2) synthesis and short-lived inhibition of exudate prostaglandin E2 (PGE2) and TXB2 synthesis. Vedaprofen also partially inhibited oedematous swelling and leucocyte infiltration into exudate. Vedap...
Ledbetter EC, Irby NL.To describe the corneal in vivo confocal microscopy (IVCM) findings in horses with putative immune-mediated keratitis (IMMK). Methods: Sixty five horses with IMMK. Methods: Horses diagnosed with IMMK were examined with a modified Heidelberg Retina Tomograph II and Rostock Cornea Module. The findings from the IVCM examinations were correlated with clinical details from ophthalmic examination and diagnostic test results. Results: Eighty eyes from 65 horses were examined. Clinical IMMK lesions were categorized as epithelial (n = 17 eyes), superficial stromal (n = 38), midstromal (n = 18), a...
Raidal SL, Rose RJ, Love DN.In this study, the effects of prolonged, high intensity training on aspects of peripheral blood and bronchoalveolar lavage (BAL)-derived leucocyte function were evaluated in 8 horses. All horses undertook a 7 week endurance training programme, followed by 5 weeks of high intensity training (HIT). Thereafter, horses were divided into control (C) and overtraining (OT) groups. The frequency and intensity of training were increased more substantially for horses in the OT group. Training was terminated in week 32 when horses in the OT group demonstrated a significant performance reduction. Peripher...
Pickles KJ, Brooks AC, Rickards KJ, Cunningham FM.N-terminal peptides derived from the anti-inflammatory peptide, annexin-1, inhibit neutrophil function but can also induce pro-inflammatory effects. Although equine annexin-1 has been sequenced, its cellular expression and properties have not been reported. This study has examined whether annexin-1 is present in equine leucocytes and how the N-terminal peptide, Ac2-26, affects equine neutrophil superoxide production. Annexin-1 expression in equine neutrophils and mononuclear cells and the ability of Ac2-26 to activate neutrophil p42/44 MAPK were determined by immunoblotting. Equine neutrophil ...
Torbeck RL, Prieur DJ.Cartilaginous defects were created in the radiocarpal joints of 12 horses. Synovial fluid cytologic features, lysozyme activity, and beta-glucuronidase activity were monitored for 16 days. A comparison was made of plasma lysozyme and beta-glucuronidase activity and of synovial fluid lysozyme, beta-glucuronidase, and leukocyte concentrations. Plasma lysozyme was found to be independent of synovial fluid lysozyme activity. Synovial fluid lysozyme was significantly increased (P less than 0.001) in all joints with surgically induced defects (group I) compared with controls (arthrocentesis done; gr...
Kleiber C, Grünig G, Jungi T, Schmucker N, Gerber H, Davis WC, Straub R.A panel of specific antibodies against CD3, CD4, CD5, CD8, MHC I and II was used in single and two colour flow cytometry to define T cell subpopulations in bronchoalveolar lavage fluid of horses affected with chronic obstructive pulmonary disease and of healthy controls. According to the results of the clinical examination including bronchoscopy and cytology of the tracheal aspirate the horses were divided into four groups (healthy, subclinically to mildly affected; moderately affected, and severely affected). All groups of horses had a similar percentage of CD3+ cells in the BALF. Compared to...
Banks EM, Kyriakidou M, Little S, Hamblin AS.Leucocytes in the lung epithelium play an important role in the ability of an animal to respond appropriately to inhaled pathogens. The distribution of lymphoid and myeloid cells associated with the lung epithelium was examined immunohistochemically throughout the respiratory tract of four horses, comprising two adults from an abattoir, one pregnant mare, and her fetus (in the final stage of gestation). Cross and tangential cryosections were labelled with monoclonal antibodies against T-cell, B-cell, macrophage/dendritic myeloid cell, and major histocompatibility Class (MHC) II surface antigen...
