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Topic:Leukocytes
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.
Lysosomal hydrolase activity in leucocytes from cattle, sheep, goats, horses and pigs. Activities of lysosomal hydrolases were measured in the leucocytes of cattle, sheep, goats, horses and pigs. There was high activity of arylsulphatase in leucocytes from cattle, high activities of alpha-fucosidase and beta-glucuronidase in leucocytes from horses and high activity of acid phosphatase in granulocytes from pigs. Within species, arylsulphatase and beta-galactosidase activities were higher in granulocytes than in mononuclear cells, but beta-glucuronidase, phosphodiesterase and alpha-galactosidase activities were higher in mononuclear cells than in granulocytes. Eosinophils of cattl...
Equine leucocyte antigen system. III. Non-MHC linked alloantigenic system in horses. A new, non-MHC linked alloantigenic membrane antigen on the equine lymphocytes is described. This antigen was characterized with alloantisera in the two-stage microcytotoxicity test and designated as ELy-1 antigen. The frequency of ELy-1 antigen positive animals in various populations is close to 50%. ELy-1 shows an autosomal, dominant inheritance. Since an allelic antigen (s) could not be demonstrated in family studies, it is assumed that only two alleles ELy-1+ and ELy-1- exist. The ELy-1 antigen in positive animals is expressed on both T and B lymphocytes but it is not present on erythrocyt...
Lymphocytes from ponies experimentally infected with equine herpesvirus 1: subpopulation dynamics and their response to mitogens. 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...
Lymphosarcoma with leukemia in a horse. A 17-year-old Arabian gelding was presented because of CNS depression and weight loss. Physical examination revealed generalized lymphadenopathy, pitting edema, and ascites. The diagnosis of lymphosarcoma with leukemic manifestations was based on cytologic and histopathologic examination of lymph node biopsy samples and a peripheral leukocyte count of 98,300/microliters, 94% of which were mature lymphocytes. These circulating lymphocytes lacked B-lymphocyte markers and did not respond to mitogenic stimulation, indicating functional incompetence. Though ultrastructural findings were equivocal, ...
Chemotaxis of horse polymorphonuclear leukocytes to N-formyl-L-methionyl-L-leucyl-L-phenylalanine. Horse polymorphonuclear leukocytes (PMN) isolated from horse blood by sedimentation and isotonic lysis and having about 25% accompanying lymphocytes were as effective at chemotaxis as nearly pure PMN isolated by density gradient techniques. N-Formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP), used as a representative of the formylmethionyl peptides (produced by prokaryocytic organisms), was effective as a chemoattractant only at the high concentration of 10(-4) M. When serum was preincubated with FMLP at concentrations as low as 10(-8) M, the serum attracted horse PMN. This activity was not g...
Effect of intra-articular injection of orgotein and saline solution on equine synovia. Orgotein was injected into the right intercarpal joint of each of 8 horses; the corresponding left joint was left alone (not injected) or was given an injection of normal saline solution. Injection with orgotein caused a transient, marked inflammatory response, evidenced by clinical signs and by increased leukocytes and total protein in the synovia (synovial fluid). Leukocyte numbers and total protein concentration were increased (P less than 0.010) in the orgotein-injected joints within 24 hours. However, saline solution alone also elicited a marked inflammatory response, manifested by increa...
Effects of dexamethasone on endotoxin shock in the anesthetized pony: hematologic, blood gas, and coagulation changes. The effects of dexamethasone (1 mg/kg of body weight) on hematologic, blood gas, and blood coagulation values in anesthetized ponies during endotoxin-induced shock were evaluated. Fifteen ponies were assigned to 3 groups of 5 ponies each: group 1, anesthetized nontreated and dexamethasone-treated controls; group 2, endotoxin, nontreated; group 3, endotoxin, dexamethasone treated. The hematologic changes in this endotoxin shock model included leukopenia and hemoconcentration. Significant hematologic effects were not seen in ponies after administration of dexamethasone. However, dexamethasone tr...
Myelomonocytic myeloproliferative diseases in a horse. Myelomonocytic myeloproliferative disease in a horse was diagnosed on the basis of hematologic, enzymatic, and histopathologic findings. It was characterized clinically by depression, weight loss splenomegaly, lymphadenopathy, coagulopathy, and bacteremia. Hematologic findings included severe refractory anemia, thrombocytopenia, monocytosis, and pleomorphic leukocytes, with a left shift of the myeloid series. The serum lysozyme concentration was 14.5 microgram/ml (normal, less than 5 microgram/ml). The bone marrow contained many immature cells of the myeloid series and had a myeloid-to-erythro...
Leukotriene generation by eosinophils. Horse eosinophils purified to greater than 98% generated slow reacting substance (SRS) when incubated with the calcium ionophore A23187. On a per cell basis, eosinophils generated four to five times the SRS produced by similarly treated horse neutrophils. Eosinophil SRS production was inhibited by 5,8,11,14-eicosatetraynoic acid and augmented by indomethacin and arachidonic acid, suggesting that it was a product(s) of the lipoxygenase pathway of arachidonic acid metabolism. Compounds with SRS activity were purified by high-pressure liquid chromatography (HPLC) and identified by ultraviolet spe...
Analysis of equine thoracic fluid. Eighteen clinically normal horses were used to study the characteristics of normal thoracic fluid. Thoracic fluid was obtained from each horse and was found to be similar to equine abdominal fluid. Total leukocytes averaged 3994/ul, total protein 1.8 g/dl, and specific gravity 1.015. Analysis of thoracic fluid from 16 horses with clinical signs of thoracic disease showed abnormalities in every case. Thoracic fluid analysis alone determined a specific diagnosis in 50% of the cases.
Subcellular distribution of particle-associated enzymes in horse neutrophil leukocytes. The subcellular components of purified neutrophil leukocytes from horse blood were fractionated by isopyknic equilibration in sucrose and metrizamide gradients. Five classes of particles have been identified: dense azurophil granules containing the bulk of the lysosomal acid hydrolase and peroxidase activity (A); less dense particles, containing all the lysozyme activity, but not resolved from a second population of azurophils B, and particles of low density, biochemically characterized as a plasma membrane fraction (C). Isopyknic equilibration in sucrose disclosed a minor membrane fraction (D...
Studies on the composition and antibacterial activity of uterine fluid from mares. Forty uterine fluid samples were obtained during oestrus and dioestrus of successive cycles from 4 mares classified as resistant to bacterial infection of the uterus. The flushings were assayed for peroxidase activity and ability to influence phagocytosis by polymorphonuclear neutrophils. Uterine fluid volumes and protein concentrations and serum oestrogen values were similar during oestrus and dioestrus. Serum progesterone concentrations were depressed during oestrus. Equine neutrophils adherent to glass slides were exposed to a genital strain of Streptococcus zooepidemicus suspended in salin...
Immunity to and immunotherapy for Rhodococcus equi. Immune responses to Rhodococcus equi were assayed in mares and foals on 7 studs in south-eastern Australia using skin test reactivity to the intradermal injection of culture filtrate and an indirect fluorescent antibody test. The prevalence of positive skin-test reactions did not differ between studs with a history of R. equi disease and those without but there were more mares with high antibody titres on studs with a disease history. A leucocyte extract prepared from mares that were skin-test positive was evaluated for its ability to protect foals exposed to experimental or natural challenge:...
Cibacron Blue-induced modification of neutral proteinase from horse blood leukocytes. The proteolytic activity of the elastase-like proteinase from granules of horse blood leukocytes is retained on a column of Cibacron Blue-Sepharose and can be eluted with 0.5 M KSCN. During this procedure its mol. wt. is reduced from 49000 to 30000 and isoelectric point is shifted towards higher pH. The inactive protein not adsorbed on Cibacron Blue-Sepharose is strongly acidic and shows a mol. wt. of 20000. Upon mixing this protein with the modified enzyme the native proteinase is reconstituted as shown by polyacrylamide gel electrophoresis at pH 8.3 and isoelectric focusing in a sucrose grad...
Haematological changes during development of acute laminitis hypertension. Experimental carbohydrate overload of 15 horses resulted in consistent haematological changes during development of laminitis hypertension. Significant alterations in packed cell volume, leucocyte differential count, serum glucose levels and protein values occurred before onset of Obel grade 3 lameness and hyperkinetic circulatory state. Blood platelets were significantly decreased 8 h after the onset of severe lameness. Findings in this study were indicative of haemoconcentration due to compartmental fluid shifts and leucocytic stress response consistent with increased circulating adrenogluco...
Isolation and identification of equine lymphocytes and monocytes. 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...
Separation and identification of equine leukocyte populations and subpopulations. Various methods of separation and identification of major equine leukocyte populations and subpopulations were used. The purity of T and B lymphocytes separated in Sephadex anti-equine F(ab')2 columns was 87% to 99% and 83% of 97%, respectively. The purity of T lymphocytes separated in nylon-wool columns was 89% to 98%. Preparations of B lymphocytes separated in glass-bead columns were 68% to 79% pure. The presence (or absence) of surface immunoglobulin by immunofluorescence was the most consistent and reliable method for the identification of B or T lymphocytes, respectively. However, the ery...
Chronic granulocytic leukemia in a horse. A nine year old quarter horse exhibited progressive weight loss and inappetance over a 47 day period. There was clinical evidence of pleuritis and pneumonia substantiated by leukocytosis and elevated protein in pleural fluid. Over the entire period the horse was neutropenic and had circulating abnormal immature granulocytes and low numbers of blast cells. Anemia and thrombocytopenia progressively worsened. Bone marrow examination revealed very few mature granulocytes but large numbers of immature cells of the granulocytic series and marked megaloblastic transformation of erythroid cells. These...
Reference values for equine peritoneal fluid. Twenty horses, aged one to 17 years (mean age 6 years), presented for elective destruction and subsequently found at autopsy to have no significant peritoneal alterations, were used to determine a variety of reference values for peritoneal fluid. Samples were collected ante mortem or within 1 h post mortem. Each cavity contained 100 to 300 ml of usually clear, pale yellow fluid which in a clinical refractometer showed a mean specific gravity 1.010 (range 1.0081-1.0116) and mean (+/- standard deviation) total protein 7.7 +/- 3.6 g/litre. The mean total nucleated cell count (+/- sd) was 4.33 +/-...
Procedure for granulokinetic studies in the horse with chromium-51. A procedure with chromium-51 (51Cr) as the cell label that maintains high-cell viability for studying granulocyte kinetics in horses is described. The procedure combines and modifies several methods for isolating leukocytes and granulocytes for use in the horse when a large volume of labeled cells is required. Also described is an improved technique for measuring granulocyte specific activity in large serial blood samples, using a Ficoll-sedimentation method. The procedure should be useful for determining granulocyte kinetics in the horse, the only major domestic species for which such data ar...
Effects of etiocholanolone and prednisolone on intravascular granulocyte kinetics in horses. The functional capacity of the marrow granulocyte reserve (MGR) in 4 adult horses was studied, using 51Cr-labeled leukocytes. The mean increase in the peripheral granulocyte count following injections of etiocholanolone (0.3 mg/kg) was 870 granulocytes/mm3, and the mean increase following prednisolone administration (200 mg) was 5,880 granulocytes/mm3. Etiocholanolone failed to mobilize the MGR and decreased the rate of granulocyte egress from the blood. Prednisolone rapidly mobilized the MGR and markedly decreased the granulocyte specific activity during the first 3 hours after injection.
Method for the automation of equine differential leucocyte counts. A technique for automating equine differential leucocyte counts by analysis of volume distribution curves using the Coulter Channelyzer has been developed and evaluated. A comparison between the results obtained by this method and standard microscopic techniques showed good agreement in most cases. Blood samples can be analysed for both differential and total leucocyte counts at a rate of 25/h. For each sample an average 16,000 leucocytes are classified by the Channelyzer. The method of volume analysis is suitable for the precise counting of polymorphonuclear neutrophils, lymphocytes and eosin...
Interaction of horse plasma antithrombin III and alpha 1-proteinase inhibitor with some serine proteinases. Antithrombin III and alpha 1-proteinase inhibitor isolated simultaneously from horse citrated plasma were tested for inhibitory activity against bovine trypsin and chymotrypsin, as well as elastase-like neutral proteinases from horse leucocytes. The stoichiometry of reaction and kinetic parameters (kass, Ko) were estimated and related to the protein pattern obtained after exposure of these proteinases to horse inhibitors as analyzed by polyacrylamide gel electrophoresis (PAGE and PAGE-SDS). As shown by fast reaction rates and low values of dissociation constants the two inhibitors effectively ...
Response of pregnant mares to equine herpesvirus 1 (EHV1). Twenty-one pregnant mares were inoculated with EHV1. Nineteen became infected as evidenced by clinical signs and/or viremia but only one mare aborted a virus-infected fetus. The viremias were leukocyte-associated and appeared to be non-productive, latent infections of these cells. Infectivity, detectable by cocultivation, persisted in the circulating leukocytes for as long as 9 days without resulting in abortion. The data suggest that it is extremely difficult to evaluate the efficacy of vaccines in preventing EHV1 (Rhinopneumonitis) abortion due to the paucity of non-exposed mares, lack of te...
Equine leukocyte antigen system. II. Serological and mixed lymphocyte reactivity studies in families. Mono- and oligospecific lymphocytotoxic alloantibodies from primiparous mares were tested on cells from horse families of various breeds in the two-step microcytotoxicity assay. The results showed that the detected antigens were inherited co-dominantly and autosomally as simple Mendelian traits. The membrane antigens showed different linkage with one or more other antigens and seem to be coded by a limited number of loci (at least three) from one chromosome. In the families tested one recombinant for the serologically defined antigens was recognized. The mixed leukocyte reactions of cells from...
