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Topic:Immune System
The immune system in horses is a complex network of cells, tissues, and organs that work together to protect the body from pathogens, such as bacteria, viruses, and parasites. This system includes both innate and adaptive immune responses, which function to identify and eliminate foreign invaders. The innate immune response provides an immediate, non-specific defense, while the adaptive immune response involves a more targeted and long-lasting protection through the production of antibodies. Key components of the equine immune system include white blood cells, such as lymphocytes and macrophages, as well as various signaling molecules like cytokines. This page compiles peer-reviewed research studies and scholarly articles that explore the structure, function, and regulation of the immune system in horses, with an emphasis on understanding its role in maintaining equine health and its response to diseases.
ADCC and complement-dependent lysis as immune mechanisms against EHV-1 infection in the horse. Immunity to equine herpesvirus type 1 (EHV-1) was evaluated using sera collected from yearling horses involved in a trial of a commercial vaccine. Measurement of the ability of these sera to mediate antibody-dependent cellular cytotoxicity and complement-dependent lysis revealed that these mechanisms, although potentially important in recovery from EHV-1 infection, do not play a role in protection following vaccination.
Increased local IgA production in chronic obstructive pulmonary disease. The immunoglobulin (Ig) content of serum and tracheal lavage fluid was measured in 50 horses suffering from chronic obstructive pulmonary disease (COPD) and 40 control horses. The mean immunoglobulin: albumin ratios of the lavage fluids of both groups were significantly higher than the corresponding values for serum, which indicates significant local production of immunoglobulins in the lower respiratory tract. The IgA: albumin ratio of lavage fluid was significantly higher in diseased compared with normal horses, which implies increased local production of IgA in this disease. The IgG: albumi...
Klossiella equi induced tubular nephrosis and interstitial nephritis in a pony. Heavy renal infection in a pony with Klosiella equi resulted in moderate diffuse tubular nephrosis and tubular rupture. Multifocal non-suppurative interstitial nephritis was associated with ruptured tubules. Ultrastructural examination of sporoblasts demonstrated both the presence of a bilaminated membrane encasing organisms and nuclear budding. Endogenous corticosteroid production probably led to the development of an immune-compromized state and subsequent extensive parasitic replication.
Severe Synovitis in Two Horses due to the Use of Irrigating Solutions Containing Methanol and Formaldehyde. Two horses were examined because of chronic lameness, which followed arthroscopy in one case, and tendon sheath lavage in a second case. Clinical investigations linked both cases to the use of irrigating fluids containing preservatives. The clinical signs were reproduced in a Shetland pony by injection and lavage of the carpal joints with the same fluid. Lameness was slow in onset and accompanied by profound periarticular fibrosis. Postmortem examination confirmed the presence of a severe, erosive, noninfectious arthritis that may have an immune-mediated component. Clinicians should read produ...
Immunoassay detection of drugs in racing horses. IV. Detection of fentanyl and its congeners in equine blood and urine by a one step ELISA assay. We have developed and evaluated a one step enzyme-linked immunosorbent assay (ELISA) test for fentanyl as part of a panel of pre- and post-race tests for narcotic analgesics in racing horses. This ELISA test detects fentanyl with an I-50 of about 100 pg/ml. The test is economical in that it can be read with an inexpensive spectrophotometer, or even by eye. The test is rapid, and ten samples, a normal pre-race complement, can be analyzed in about twenty minutes. The test readily detects the presence of fentanyl or its metabolites in equine blood and urine from two and twenty-four hours respecti...
Duration of circulating antibody and immunity following infection with equine influenza virus. The duration of immunity as measured by virological, serological and clinical responses following infection with influenza A/equine/Newmarket/79 (H3N8) was assessed in repeated challenge experiments in which ponies were infected by exposure to aerosols of infectious virus. Previous infection stimulated complete clinical protection which persisted for at least 32 weeks as demonstrated by the absence of febrile responses and coughing in two groups of ponies infected 16 weeks or 32 weeks after the first infection. Partial clinical protection persisted for over a year as demonstrated by the absenc...
Ciliated protozoa in the colonic wall of horses. Ciliated protozoa of several morphological types were found in the colonic tissue of 8 horses, mostly immature Standardbreds. Most of the protozoa observed appeared similar to those normally found as commensals in the equine large intestinal lumen. In all cases, organisms were located in the lamina propria; organisms were also found in the submucosa of 2 horses. The association of colonic disease with the presence of intramural ciliates was unclear.
Immunoassay detection of drugs in racing horses. III. Detection of morphine in equine blood and urine by a one step ELISA assay. A one step enzyme-linked immunosorbent assay (ELISA) test for morphine was evaluated as part of a panel of pre- and post-race tests for narcotic analgesics in racing horses. This ELISA test is very sensitive to morphine with an I-50 for morphine of about 400 pg/ml. The test is also rapid, and ten samples, a normal pre-race complement, can be analyzed in about thirty minutes. The test can be read with an inexpensive spectrophotometer, or even by eye. The test readily detects the presence of morphine or its metabolites in equine blood for up to six hours after administration of sub-therapeutic d...
Noncatalytic protein component of elastase from horse leucocytes. A protein with regulatory function. 1. Noncatalytic protein component (NPC), a strongly acidic protein (pH = 4.5) was separated from native horse leucocyte elastase 1. 2. This protein reduces elastinolytic properties of elastases: 1 and 2A probably by decreasing their isoelectric points. 3. A possible regulatory role of this protein may be inferred from a higher affinity of elastase 1 to NPC rather than to elastin.
Platelet activating factor as a mediator of equine cell locomotion. Equine polymorphonuclear (PMN) and mononuclear (MN) leucocytes were separated on Percoll gradients and used to study the chemoattractant properties of the polar ether-linked phospholipid, platelet activating factor (PAF). Six concentrations of PAF ranging from 1 ng/ml to 100 micrograms/ml were studied in each of two in vitro assay systems, the agarose microdroplet and a microfilter technique. Very significant (p less than 0.01) increases in the movement of both PMN and MN cells were obtained with most concentrations of PAF. In two instances there was no apparent concentration-response relation...
T lymphocyte development and maturation in horses. Monoclonal antibodies specific for equine T lymphocyte subpopulations were produced and procedures for the continuous culture of equine lymphocytes were developed. These reagents and procedures were used to analyse the appearance, maturation and functions of T lymphocytes in normal horses and in T lymphocyte deficient horses with severe combined immunodeficiency (SCID). T lymphocytes appeared as early as the 75th day of fetal development and were normally distributed prior to birth of normal foals. Analysis of thymic T lymphocyte differentiation in SCID foals revealed the presence of both prot...
Human recombinant interleukin-2(125) induced in vitro proliferation of equine, caprine, ovine, canine and feline peripheral blood lymphocytes. Equine, caprine, ovine, canine and feline peripheral blood lymphocytes were evaluated in a short term dose-response study for their in vitro blastogenic responsiveness to human recombinant interleukin-2(125) (HrIL-2(125] alone or in combination with phytohemagglutinin-P, concanavalin-A, and pokeweed mitogen. HrIL-2(125) induced lymphocyte proliferation in all of the animals tested. The magnitude of the proliferative response varied among the species of animal tested. In all cases the proliferative response was dependent on the concentration of HrIL-2(125). HrIL-2(125) at a minimum concentratio...
Defective thymocyte maturation in horses with severe combined immunodeficiency. Six monoclonal antibodies, designated EqT2, EqT3, EqT6, EqT7, EqT12, and EqT13, which identify T lymphocyte antigens present at different stages of T cell maturation were used to examine T lymphocyte development in foals with severe combined immunodeficiency (SCID). Flow microfluorimetry demonstrated the presence of EqT12+ and EqT13+ prothymocytes and a few phenotypically mature EqT2+ and EqT3+ thymocytes within the thymic remnants of SCID foals. However, very few EqT6+ and EqT7+ resident cortical thymocytes were detected. The near absence of EqT6+ and EqT7+ cortical thymocytes was confirmed b...
Evaluation of foals for immune deficiency disorders. Currently recognized equine immune deficiency disorders include failure of passive colostral immunoglobulin transfer, combined immunodeficiency, selective IgM deficiency, transient hypogammaglobulinemia, and agammaglobulinemia. Additional equine immune deficiency disorders probably exist. Immune deficiency should be suspected in any horse experiencing persistent or recurrent infections that are not responsive to conventional therapy.
Immunologic reconstitution of foals with combined immunodeficiency. Thirty-eight foals with combined immunodeficiency (CID) received transplanted fetal liver cells, fetal liver and thymus cells, histocompatible bone marrow cells, or equine lymphocyte antigen (ELA) haploidentical bone marrow cells in an attempt to reconstitute their deficient immune systems. Engraftment was infrequent, partial, and unpredictable when fetal cells were employed. Three of five CID foals receiving ELA haploidentical bone marrow cells demonstrated partial reconstitution, but engraftment was only temporary. Administration of histocompatible bone marrow cells resulted in rapid, full a...
Role of the host immune response in selection of equine infectious anemia virus variants. Equine infectious anemia virus was isolated from peripheral blood leukocytes collected during two early febrile cycles of an experimentally infected horse. RNase T1-resistant oligonucleotide fingerprint analyses indicated that the nucleotide sequences of the isolates differed by approximately 0.25% and that the differences appeared randomly distributed throughout the genome. Serum collected in the interval between virus isolations was able to distinguish the isolates by membrane immunofluorescence on live cells. However, no neutralizing antibody was detected in the interval between virus isola...
The use of a passive hemolysis system to evaluate the complement activities of six mammalian species. A passive hemolysis assay system was developed which permitted comparisons of the hemolytic activities of complement (C) from six species. This system employs a single antigen and an antiserum raised in one species. Thus, variations resulting from different target antigens and those inherent in using antibodies (of different affinities and isotypes) raised in a variety of species were minimized. Of the erythrocytes (E) examined, those from horses and guinea pigs were most susceptible to lysis, and either would be suitable, as a tentative choice, for measuring C activity of a previously unstudi...
Assessment of neutrophil migration, phagocytosis and bactericidal capacity in neonatal foals. Comparison of neutrophil function was made between 8 clinically normal pony foals (3 to 7 days of age), and their dams. Random migration, stimulated migration to zymosan-activated serum, bacterial phagocytosis and bactericidal capacity of neutrophils were determined in vitro. Random migration was greater (P less than 0.01) and stimulated migration was less (P less than 0.01) in foals than in their dams. Bacterial phagocytosis and bactericidal capacity of neutrophils were not different (P greater than 0.05) between foals and mares. Results of this study suggested that neonatal foals have altere...
[Isolation and purification of proteolytic enzymes on organo-silica sorbents with immobilized gramicidin S]. Biospecific sorbents for affinity chromatography of proteolytic enzymes have been synthesized by attaching cyclopeptide antibiotic gramicidin S to organo-silica supports. It is shown possible to attach gramicidin S to the organo-silica supports using glutaric aldehyde, p-benzoquinone, soluble and insoluble carbodiimides. The sorbents prepared by these methods were successfully applied for the purification of the crude pepsin from horse gastric juice and proteolytic complex produced by Acremonium chrysogenum.
Effect of estradiol and progesterone on antistaphylococcal activity of neutrophils from ovariectomized mares. Neutrophils isolated from jugular blood of ovariectomized mares were studied for the effect of estradiol and progesterone on bactericidal activity against Staphylococcus aureus. In experiment 1, neutrophils obtained from 4 mares were tested for bactericidal activity by adding estradiol (43 pg/ml) or progesterone (6.4 ng/ml) to the bactericidal assay. In experiment 2, 3 of the 4 ovariectomized mares were given 2 mg of estradiol, IM, daily for 3 days. Eighteen days after the initial estradiol injection, mares were given 300 mg of progesterone, IM, for 6 days. Neutrophils from these mares were te...
Genetic restriction of cytolysis during equid herpesvirus 1 subtype 2 infection. Six Welsh Mountain pony foals were experimentally infected with a subtype 2 isolate of Equid Herpesvirus 1 (EHV-1) and subsequently examined for T cell mediated cytotoxicity against both subtypes. Cytotoxicity was not observed at 3 or 7 days after primary exposure but virus-specific, and genetically restricted, cytotoxicity of EHV-1-labelled autologous skin fibroblasts could be demonstrated 7 and 21 days after the animals were given a second exposure to live virus. Killing of subtype 2 antigen-labelled targets was more efficient than subtype 1 coated cells. This finding was paralleled by the o...
Immunoassay detection of drugs in horses. I. Particle concentration fluoroimmunoassay detection of fentanyl and its congeners. We investigated the use of particle concentration fluorescence immunoassay (PCFIA) as a technique for drug detection in racing horses. The test was constructed from an antiserum to a carboxyfentanyl-BSA conjugate and carboxyfentanyl linked to b-Phycoerythrin. Using these reagents and a PCFIA apparatus levels of fentanyl as low as 0.1 ng/ml could be detected by the assay. In addition, cross-reactivity studies on this assay showed that the anti-serum cross-reacted well with carfentanil, sufentanil and the methylated analogs of fentanyl. We therefore evaluated the ability of these agents to produ...
The histological features of the immune system of the equine respiratory tract. The distribution of mucosa-associated lymphoid tissue along the equine respiratory tract was surveyed in light microscopical sections. Intra-epithelial lymphocytes and similar cells scattered in the lamina propria were identified in all sites from the nasal vestibule to bronchioles of 2 to 4 mm diameter. Isolated lymphoid patches, occasionally with nodules, were common in bronchioles, but the density of this bronchiole-associated lymphoid tissue (BRALT) varied between individual horses. Bronchus-associated lymphoid tissue (BALT) was infrequently encountered. In the upper respiratory tract, nod...
Cutaneous vasculitis in horses: 19 cases (1978-1985). The medical records of 19 horses with cutaneous vasculitis were reviewed. Most (73.7%) affected horses were between 3 and 10 years old, and there were significantly more mares (14) than stallions or geldings (5) (P less than 0.01). Subcutaneous edema of the limbs, body, and/or head was the predominant clinical sign (18/19 horses; 94.7%). The single most prevalent laboratory abnormality was neutrophilia (greater than 7,000 neutrophils/microliter), which was detected in 10 horses (52.6%). Leukocytoclastic vasculitis was evident in skin biopsy specimens from 12 of 14 horses (85.7%). All horses we...
The binding domain on horse cytochrome c and Rhodobacter sphaeroides cytochrome c2 for the Rhodobacter sphaeroides cytochrome bc1 complex. The interaction of the Rhodobacter sphaeroides cytochrome bc1 complex with Rb. sphaeroides cytochrome c2 and horse cytochrome c was studied by using specific lysine modification and ionic strength dependence methods. The rate of the reactions with both cytochrome c and cytochrome c2 decreased rapidly with increasing ionic strength above 0.2 M NaCl. The ionic strength dependence suggested that electrostatic interactions were equally important to the reactions of the two cytochromes, even though they have opposite net charges at pH 7.0. In order to define the interaction domain on horse cytochro...
Large granular lymphocytes from SCID horses develop potent cytotoxic activity after treatment with human recombinant interleukin 2. Peripheral blood mononuclear cells from foals with hereditary severe combined immunodeficiency (SCID) have morphologic characteristics of large granular lymphocytes (LGL). Attempts to demonstrate cytotoxic activity were without success unless the LGL were incubated with 100 U of human recombinant interleukin 2 (rIL 2)/ml for 24 hr. With rIL 2 incubation, low effector to target ratios (10:1) consistently yielded high levels of cytotoxic activity (30 to 50%) in a standard 4-hr 51Cr-release assay using YAC-1 lymphoma or K562 erythroleukemia cell lines as targets. Monoclonal antibody EqT12 reacted...
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...
Immune-mediated hemolytic anemia induced by penicillin in horses. Three horses developed severe, immune-mediated hemolytic anemia after treatment with penicillin. The horses had positive direct antiglobulin (Coombs) tests and high titers of IgG antibody that agglutinated penicillin-coated equine red cells. Two of the horses were tested for antibodies to autologous red cell antigens; autoantibodies were not present. Titers of antipenicillin antibody decreased after penicillin was discontinued but IgG antibody was detectable months after recovery. One of the horses was challenged with penicillin; antibody titer increased slightly, but anemia did not develop. A...
