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.
Cellular and humoral defence mechanisms in mares susceptible and resistant to persistent endometritis. Both random and directional migration of blood neutrophils from 9 mares susceptible to persistent endometritis were significantly less (p less than 0.05) than neutrophils from 8 resistant mares. Serum from susceptible mares had significantly more (p less than 0.01) chemotactic activity than serum from resistant mares. Although phagocytosis of yeast blastospores by blood neutrophils from 4 resistant and 3 susceptible mares was similar, uterine neutrophils from susceptible mares were significantly worse (p less than 0.01) at phagocytosis than uterine neutrophils from resistant mares. Uterine was...
Evaluation of granulocyte transfusion in healthy neonatal pony foals. Granulocyte transfusions (GT), 0.98 X 10(9) neutrophils/kg of body weight, were performed on 7 healthy pony foals between 2 and 7 days old. The mean neutrophil count of the foals was significantly (P less than 0.05) greater than base line (4,830 +/- 1,260/microliter) 1 hour after GT (8,870 +/- 3,350/microliter) and was similar to base line by 15 to 18 hours after GT (6,550 +/- 2,310/microliter). Leukocyte concentrates (LC) used for GT were harvested from clinically normal adult horses by continuous-flow centrifugation leukapheresis (CL), 3 to 6 hours after hydrocortisone sodium succinate was a...
The interaction of Rhodococcus equi and foal neutrophils in vitro. Polymorphonuclear neutrophil leukocytes (PMNL) from 8 healthy foals (2-14 weeks of age) and 2 foals with bacterial pneumonia were separated from whole blood using a 2 step Percoll gradient. Purified PMNL were tested for bactericidal function against Rhodococcus equi and Staphylococcus aureus in the presence of normal horse serum. The percentage uptake after a 15-min pre-incubation of PMNL and bacteria was also calculated. Ultrastructural examination of the interaction of R. equi and normal foal PMNL was performed after 15 min incubation. Results indicated that foal PMNL effectively phagocytose...
Influence of chemotactic agents on the locomotion of equine polymorphonuclear and mononuclear leucocytes. Subpopulations of equine leucocytes, polymorphonuclear and mononuclear cells, were separated from whole blood on a discontinuous Percoll gradient and used in studies of chemokinesis and chemotaxis. Polymorphonuclear cells responded to the chemo-attractant properties of zymosan-activated plasma in Boyden chamber and agarose microdroplet assays but they responded only slightly (Boyden chamber) or not at all (agarose microdroplet) to the peptide N-formyl-methionyl-leucyl-phenylalanine (FMLP). Equine mononuclear cell movement was increased by FMLP in both assay systems and these cells also respond...
Pulmonary aspergillosis in a horse with myelomonocytic leukemia. Acute myelomonocytic leukemia was diagnosed in a 2-year-old Standardbred mare that had hind limb edema and fever unresponsive to antibiotics. The mare had anemia, thrombocytopenia, and leukocytosis, with circulating myeloblasts and monocytoid cells. A bone marrow specimen was hypercellular, with myeloblasts and monocytoid cells. Peroxidase, chloroacetate esterase, and alpha naphthyl acetate esterase activities were detected in many bone marrow cells. Interstitial pulmonary densities were seen radiographically. The mare was euthanatized and necropsied. Infiltrates of leukemic cells were found m...
Actions of non-steroidal anti-inflammatory drugs on equine leucocyte movement in vitro. The direct effects of four non-steroidal anti-inflammatory drugs (NSAIDs) on equine polymorphonuclear (PMN) and mononuclear (MN) leucocyte movement were investigated using two in vitro assay systems. The Boyden chamber microfilter technique measures both chemokinetic and chemotactic locomotion, and the agarose microdroplet assay measures solely chemokinesis. Zymosan-activated plasma (ZAP) and the synthetic peptide N-formyl-methionyl-leucyl-phenylalanine (FMLP) were used as standard chemoattractants for PMN and MN leucocytes, respectively. The actions of six concentrations of each NSAID, indome...
Development of equine models of inflammation. The Ciba-Geigy Prize for Research in Animal Health. Two experimental models of acute non-immune inflammation have been developed to enable studies of the biochemical composition and cellular content of exudates to be undertaken. Both are based on the creation of a mild, reproducible and reversible inflammatory reaction, which is free from uncontrolled incidental factors and which causes minimal distress to the experimental animals. The polyester sponge model involves the insertion of small polyester sponge strips soaked in sterile carrageenan solution into subcutaneous neck pouches and their serial removal. The tissue-cage model is based on the...
Cellular aspects of inflammation. The Ciba-Geigy Prize for Research in Animal Health. The migration of leucocytes to sites of acute and chronic inflammation is an event of central importance to the maintenance of inflammatory processes; extravascular leucocytes are responsible for generating chemical mediators of inflammation and the phagocytosis of particulate matter. They may also be involved in the conversion of acute to chronic inflammatory lesions. Leucocytes are attracted to sites of tissue injury by a range of chemoattractants. This paper describes the development of a method for separating on Percoll gradients purified populations of equine polymorphonuclear and mononuc...
Effect of povidone-iodine on in vitro locomotion of equine neutrophils. Incubation of equine neutrophils with povidone-iodine solutions of greater than or equal to 0.2 per cent resulted in total inhibition of migration under agarose. This was caused by the cytotoxic effects of the solutions as shown by pyknosis and cell lysis. Lower concentrations of povidone-iodine, however, did not adversely affect neutrophil viability or locomotion.
Bactericidal activity of peripheral blood neutrophils during the oestrous cycle and early pregnancy in the mare. The oestrous cycles of 20 mixed-breed mares were synchronized with daily injections of 10 mg oestradiol-17 beta and 150 mg progesterone given i.m. for 10 days. On the 10th day, 10-15 mg prostaglandin F-2 alpha was administered i.m. to induce oestrus. Neutrophils were isolated from jugular blood on the 2nd or 3rd day of oestrus, Days 5 and 7 after ovulation or during early pregnancy (Days 18-34 of pregnancy). Neutrophils were challenged with Staphylococcus aureus and their bactericidal activity examined after 30 and 120 min of incubation for a reduction of colony forming units. Bactericidal act...
Actions of BW540C in an equine model of acute inflammation: a preliminary study. An equine model of acute non-immune inflammation has been developed to facilitate studies of the inflammatory process and the actions of novel anti-inflammatory drugs. Five polyester sponge strips soaked in sterile 2% carrageenin solution were placed in subcutaneous pouches prepared under local anaesthesia in the necks of conscious ponies. Serial removal of the strips and harvesting of the exudate enabled studies to be made of the cellular, biochemical and mediator aspects of the localised, acute inflammation, and the heat generated by the lesion was monitored by infra-red thermometry. Maximal...
Opsonins of Streptococcus in uterine flushings of mares susceptible and resistant to endometritis: control of secretion and partial characterization. The release of opsonins into the uterine lumen of mares susceptible or resistant to endometritis was examined after intrauterine inoculation of a filtrate of Streptococcus culture fluid or vehicle. Uterine flushings were collected at 0.5 hour before and 2, 4, 6, 8, and 24 hours after inoculation on day 2 or 3 of estrus and on day 7 or 8 after ovulation. Amounts of opsonins in flushings were quantified as the H2O2 produced by leukocytes incubated with flushings-opsonized bacteria, compared with H2O2 produced by leukocytes incubated with nonopsonized bacteria. Opsonin values in flushings increas...
An induced synovitis disease model in ponies. The effects of intra-articular injection of small amounts of E. coli lipopolysaccharide (LPS) into the intercarpal joint of 5 ponies were studied. The LPS induced predictable changes all of which were analogous to acute bacterial infection, except that the development of signs occurred sooner after the LPS injection, and subsided within 36 hours. Fever was monophasic and peaked at 5-7 hours. The ponies exhibited depression, reduced or absent appetite, increased pulse and respiration rates, and lameness. The lameness became evident between 1 and 2 hours after injection, at which time warmth, ar...
Modification and evaluation of a multichannel blood cell counting system for blood analysis in veterinary hematology. A multichannel, semiautomated, blood cell counting system (Coulter Counter Model S550) was modified for use in veterinary hematology by increasing both the erythrocyte and leukocyte aperture currents to 225 V and 195 V, respectively, followed by calibration with human blood. It was evaluated by use of 350 samples from dogs, cats, horses, and cows. Values for leukocyte count, erythrocyte count, mean corpuscular volume, and hematocrit generated by the S550 were compared with values generated by an automated multichannel counter with histogram capability and other reference procedures when approp...
Effects of stallion seminal plasma on hydrogen peroxide release by leukocytes exposed to spermatozoa and bacteria. The ability of stallion seminal plasma to modify phagocytosis of spermatozoa and Streptococcus zooepidemicus was examined. Phagocytosis was monitored indirectly as the H2O2 produced by peripheral blood leukocytes after addition of spermatozoa or bacteria. Hydrogen peroxide production after addition of ejaculated spermatozoa was greater (P less than 0.01) than after addition of epididymal sperm. Furthermore, pre-incubation of epididymal sperm with 6.25-50% seminal plasma caused a dose-dependent increase in subsequent H2O2 production by leukocytes (P less than 0.05). In addition, equine serum wa...
Extraspecific donkey-in-horse pregnancy as a model of early fetal death. Transfer of donkey embryos to horse mares provides a useful model of early fetal death. Endometrial cups do not develop in this one type of extraspecific pregnancy and 80% of donkey fetuses are aborted between Days 80 and 100 of gestation in conjunction with abnormal implantation and an intense accumulation of leucocytes in the endometrium of the surrogate mare. Treatment of mares carrying donkey conceptuses with progestagen (allyl trenbolone) or purified horse chorionic gonadotrophin does not prevent abortion. However, passive immunization with serum from mares carrying intraspecific horse fe...
Pathogenesis of degenerative joint disease. Proteoglycan degradation is central to the development of degenerative joint disease. Proteoglycans may be degraded by lysosomal enzymes from chondrocytes, synoviocytes or leucocytes. Collagen and matrix degradation occurs either by direct damage or due to degrading enzymes released into synovial fluid. Once the pathological sequence has begun it continues in a cyclic manner unless arrested by the ability of chondrocytes to synthesise sufficient matrix components. Treatment should ideally be directed to this end.
[Histogenesis of granulation tissue in wound healing by second intention in horses and cattle]. An experiment in comparative developmental aspect was carried out with 5 horses and 5 cattle having a total of 60 skin and muscular wounds. Light microscopic studies on hematoxylin-eosin stained preparations revealed that the dystrophic changes in the underlying tissues were more strongly manifested in horses. This had to be taken into consideration in the surgical treatment of wounds with this animal species. The basic differences comprised the better manifested leukocytic reaction in horses and the more strongly expressed processes of growth and differentiation on the part of the connective ...
Clinical and hematologic variables in ponies with experimentally induced equine ehrlichial colitis (Potomac horse fever). The clinical and hematologic variables of 10 ponies with experimentally induced equine ehrlichial colitis (EEC; syn: Potomac horse fever) were studied for a 30-day period (6 ponies) or until death (4 ponies). The earliest clinical sign indicative of EEC was fever (rectal temperature exceeding 39 C). All ponies became depressed (CNS) at various times during the disease, and 90% of the ponies developed diarrhea between 9 and 15 days after infection was induced. The most significant hematologic change was an increase in plasma protein concentration after the onset of fever (P less than 0.05). The...
Chemotactic and phagocytic function of peripheral blood polymorphonuclear leucocytes in newborn foals. Chemotactic and phagocytic responsiveness of peripheral blood polymorphonuclear leucocytes (PMNLs) from 11 foals were analysed immediately after birth (pre-colostral) and at different times after colostrum ingestion. The number of foal PMNLs per microscopic field that had migrated through the filter in chemotaxis and the number of yeast particles ingested per foal PMNL in phagocytosis were significantly lower when tested with foal plasma before colostrum ingestion (chemotaxis, 2.0 +/- 0.55 (s.e.m.); phagocytosis, 0.98 +/- 0.352) than in tests 4 or more days after colostrum ingestion (chemotaxi...
Phagocytosis of horse erythrocytes treated with equine infectious anemia virus by cultivated horse leukocytes. Horse erythrocytes treated with equine infectious anemia virus hemagglutinin were phagocytized by cultivated horse leukocytes (mainly macrophage-like cells and partly polymorphonuclear cells) after incubation with fresh horse serum but not with inactivated horse serum. The phagocytosis began as soon as the erythrocytes were added to the leukocyte cultures, and the majority of the reaction proceeded within 30 minutes. Addition of antiserum showed a slightly suppressing but no enhancing effect on the phagocytosis. Phagocytosis seemed to be caused by the recognition of the third complement compon...
Cervico-endometrial cytology and physiological aspects of the post-partum mare. After parturition, Thoroughbred mares were mated at the first post-partum oestrus (N = 24) or at a subsequent oestrus (N = 12). All mares were examined daily for: oestrous detection, palpation per rectum of the genital tract, vaginoscopic examination and cervico-endometrial cytology. Pregnancy diagnosis was carried out at Days 18, 35 and 45 after mating. An identical first service conception rate of 50% was found in both groups. The number of neutrophils followed a descending profile to only scattered cells at the first post-partum oestrus and in Group II mares remained at this very low level ...
Single step purification procedure for the rapid separation of equine leucocytes. Percoll gradients have been used to separate relatively pure populations of viable equine polymorphonuclear (PMN) and mononuclear (MN) cells. In preliminary studies, a continuous density gradient of 70% Percoll solution was used to separate two distinct leucocyte-rich bands. After measurement of the density of each band on the continuous gradient, discontinuous Percoll gradients, using 60% and 75% Percoll solutions, were used to provide a rapid means of separating PMN and MN cells. The yield of viable cells per ml of blood was 3.0 X 10(6) and 3.2 X 10(6) for MN and PMN cells, respectively. Cor...
Effects of a phenylbutazone paste in ponies: model of acute nonimmune inflammation. In a 12-day treatment schedule, 5 ponies were given orally a paste formulation of phenylbutazone (PBZ) and 5 matched ponies were given equivalent doses of a placebo paste. On day 12, a mild, nonimmune inflammatory reaction was induced subcutaneously in the neck of each pony by inserting sterile, polyester sponge strips soaked in a 2% carrageenan solution. Exudate was collected at 4, 8, 12, and 24 hours by serial removal of sponges. There were no significant (P less than 0.05) differences in exudate protein concentration and leukocyte numbers between the treatment groups, but the group given PB...
Quantitative buffy coat analysis of blood collected from dogs, cats, and horses. Using quantitative buffy coat analysis (QBCA), rapid and accurate measurements can be made of the erythrocyte PCV, total WBC count, and platelet count, and the leukocyte population can be differentiated into total granulocytes (including quantitation of eosinophils), and lymphocytes and monocytes. The QBCA is performed by placing a blood sample (50 to 111 microliters) into a high-precision-bore microhematocrit tube that contains a freely moving, closely fitting, cylindrical plastic float. After centrifugation for 5 minutes, the buffy coat components separate by density. The plastic cylinder fl...
Innate immunity during Equid herpesvirus 1 (EHV-1) infection. Intrinsic phagocytosis and killing of C. albicans by equine monocytes and polymorphonuclear leucocytes (PMN) was examined during Equid Herpesvirus 1 (EHV-1) (subtypes 1 or 2) and Adenovirus infections. Monocyte function increased during EHV-1 subtype 2 and Adenovirus infection. Conversely, there was an impairment of monocyte ingestion during EHV-1 subtype 1 infection which was ascribed to virus replication in peripheral blood mononuclear cells. PMN phagocytosis was not decreased in any of the infections studied. The raised levels of haemolytic complement in animals which subsequently developed...
Adverse effects following intravenous fluid therapy in the horse using non-commercial fluids: preliminary findings. Non-commercial, endotoxin positive, intravenous fluids as well as a commercially available intravenous fluid were given to clinically normal horses. Endotoxin-positive fluids caused clinical signs attributable to endotoxaemia. Leukopenia, preceded by a fluctuating white cell count, was observed in horses showing clinical signs. The commercial intravenous fluid had no effect on the white cell count or on the clinical state. Precautions to be taken and recommendations are made with regard to the monitoring of horses in which one might be forced to use non-commercial intravenous fluids.
Evaluation of leukapheresis and thrombocytapheresis in the horse. Continuous-flow centrifugation leukapheresis techniques were used to collect 300-ml volumes of leukocyte-rich plasma from 5 nonmedicated horses and from 5 corticosteroid-stimulated horses. White blood cell counts and differential counts were performed on the horses before (base line) and up to 48 hours after leukapheresis. Systemic administration of hydrocortisone increased numbers of total WBC and neutrophils and improved harvest of these cells. Nonmedicated horses had a mean yield of 3.38 X 10(10) leukocytes in the 300-ml volume. Stimulated horses yielded a mean of 6.88 X 10(10) leukocytes. ...
Continuous-flow centrifugation hemapheresis in the horse. In a continuous-flow centrifugation apheresis technique adapted for blood-component separation and collection in horses, hydroxyethyl starch was not required for erythrocyte sedimentation. The efficacy and separation characteristics of whole blood from 10 horses were evaluated at various gravitational forces (700 to 1,500 rpm), using a constant withdrawal rate (100 ml/min). Maximum leukocyte collection occurred at 700 rpm (P less than 0.01), and optimal neutrophil collection occurred at 700 to 750 rpm (P less than 0.01). Although neutrophil counts decreased and lymphocyte counts remained const...
In vitro bactericidal efficacy of equine polymorphonuclear leukocytes against Corynebacterium equi. Polymorphonuclear leukocytes from adult horses were separated from whole blood, using a 2-step Percoll gradient, and were tested for bactericidal function against Corynebacterium equi. Staphylococcus aureus, an organism against which equine neutrophils have proved efficacy, was a positive control. The percentage of uptake after a 15-minute preincubation of the neutrophils and bacteria in the presence of normal horse serum was also calculated. The results indicated that equine neutrophils effectively phagocytosed and killed C equi and S aureus. The percentage of uptake for S aureus (95% +/- 3%)...