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Topic:Immune Response
The immune response in horses involves a complex network of cells, tissues, and molecules that work together to protect the animal from pathogens and other harmful agents. This process includes both innate and adaptive immune mechanisms. Innate immunity provides the first line of defense and involves components such as physical barriers, phagocytic cells, and the complement system. Adaptive immunity, on the other hand, is characterized by the activation of lymphocytes and the production of antibodies, which provide a targeted response to specific antigens. Key components of the equine immune system include T cells, B cells, and various cytokines that facilitate communication between immune cells. This page compiles peer-reviewed research studies and scholarly articles that explore the mechanisms, regulation, and implications of immune responses in equine health.
Plasma endotoxin concentrations in experimental and clinical equine subjects. Endotoxin (LPS) was quantitated in experimental subjects and in horses with naturally occurring gastrointestinal strangulation obstruction and/or septicaemic diseases to establish the fate of LPS and the clinical usefulness of the Limulus amoebocyte lysate (LAL) assay. The assay was validated for sensitivity (10 pg/ml), recovery (90 to 106 per cent), intra-assay precision (CV = 5.5 per cent) inter-assay precision (CV = 11 per cent), and stability of diluted, heat treated, frozen samples (at least 90 days). Plasma concentrations of LPS after sublethal (3 micrograms/kg) jugular or portal vein bo...
Serological response of experimental ponies orally infected with Ehrlichia risticii. Ten healthy, mature ponies were orally infected with Ehrlichia risticii using Ehrlichia-infected P388D1 mouse monocyte tissue culture cells. Seven developed signs of equine ehrlichial colitis including fever, depression, anorexia, reduced borborygmi, increased abdominal hyperresonance, and diarrhoea. Three remained clinically normal apart from early fever in one. Indirect fluorescent antibody titres were detected in the clinically affected ponies by Days 12 to 17 post infection and increased rapidly to high levels (1:640 to 1:5120) which were maintained until the end of the observation period ...
[Training of the immune system of foals against ERP virus infections by frequent vaccination with presently available commercial vaccines]. During 3 foaling seasons around 150 Lipizzaner foals were vaccinated against ERP with commercial vaccines and groups thereof were serotested in CF and SN for their humoral immune response. In addition, 6 horses of cheaper common breeds were vaccinated on the University premises, were continuously serologically screened and subjected to virulent nasal test infection. The live-virus vaccine Prevaccinol interfered so profoundly and up to the 20th week of life with maternal antibodies that its further use was discontinued. The inactivated vaccine Pneumabort-K proved to be of impressive immunogenic...
Antibody isotype responses in the serum and respiratory tract to primary and secondary infections with equine influenza virus (H3N8). Serum antibody (IgGab, IgM and IgA) responses to primary and secondary infection with influenza A/equine/Newmarket/79 (H3N8) by nebulised aerosol were compared with local (nasopharyngeal and tracheal) antibody responses in ponies. Circulating IgGab antibody was of long duration after primary infection, whereas IgM responses were short-lived after both primary and secondary infections. The antigenic stimulation of secondary infection with equine influenza was sufficient to induce elevations of serum IgM and IgA in the presence of high levels of circulating IgGab. These results support the poten...
Serum amyloid A protein (SAA) in horses: objective measurement of the acute phase response. A sensitive and precise immunoassay for equine serum amyloid A protein (SAA) was established and used to determine, for the first time, the circulating concentration of this protein in health and disease. As in other species, equine SAA was present only at trace levels in healthy animals but behaved as an extremely sensitive and rapidly responding acute phase reactant following most forms of tissue injury, infection and inflammation, objectively reflecting the extent and activity of disease. Measurements of SAA should make a significant contribution to diagnosis and management of viral and bac...
Identity of the E-series prostaglandin produced by equine chondrocytes and synovial cells in response to a variety of stimuli. Although an E-series prostaglandin has previously been identified in equine inflammatory exudate, the identity of this eicosanoid as PGE2 has not been confirmed. The objective of this study was the specific characterisation of the prostaglandin produced by equine cells in the presence of an inflammatory stimulus. By using two radioimmunoassays, a relatively non-specific PGE2 assay and a more specific PGE1 assay, it has been possible to identify the E-series prostaglandin produced by equine chondrocytes and synovial cells, in response to a variety of stimuli, as PGE2.
Maternal immunological recognition of pregnancy in equids. There is little evidence for maternal immunological recognition of pregnancy in most species with the striking exception of the members of the genus Equus. Almost all mares make strong cytotoxic antibody responses to paternally inherited fetal antigens by Day 60 of gestation. Most of these responses are directed against antigens of the Major Histocompatibility Complex (MHC), which constitutes the primary immunogenetic barrier to successful organ transplantation. The source of fetal MHC antigens in the pregnant mare appears to be the specialized trophoblast cells of the chorionic girdle region ...
[The early chemotactic reaction of the equine uterus to acute inflammatory stimulation]. The uteri of normal pony mares in oestrus were infected experimentally with Streptococcus zooepidemicus. Uterine contents were collected 30, 60, 120 or 240 minutes later and were tested for their chemotactic effect on equine-neutrophils both with a morphological assay based on neutrophil shape changes and with a modified Boyden chamber technique. By 30 minutes after infection the uterine contents were markedly chemotactic for isolated peripheral neutrophils and remained so at the 240-minute collection. Uterine contents from uninfected mares had minimal chemotactic properties. These results cou...
Immunization of equines with phospholipase A2 protects against the lethal effects of Crotalus durissus terrificus venom. Equines (2 horses and 2 donkeys) immunized with whole Crotalus durissus terrificus venom or its phospholipase A2 component either presented an increased survival time determined 3 days after challenge or were totally resistant to a challenging lethal dose of 200 mg crude venom 270 days after the initial immunization or 90 days after the last booster injection. The resistance was demonstrable on the basis of a good correlation with antibody titers determined by the ELISA method but not with the flocculation and neutralization assays. Since phospholipase A2 is essentially nontoxic, it can be use...
Preliminary investigations on the effects of a Strongylus vulgaris larval extract, mononuclear factors and platelet factors on equine smooth muscle cells in vitro. Factors involved in the proliferation of equine vascular smooth muscle cells were studied in vitro. The most prominent proliferative responses in cultured vascular smooth muscle cells were induced by Strongylus vulgaris larval antigen extract (LAE) and platelet-derived factors. Less significant proliferative responses were obtained with conditioned media from S. vulgaris LAE stimulated and from unstimulated equine mononuclear leukocytes. Additionally, vascular smooth muscle cells exposed to S. vulgaris LAE developed numerous perinuclear vacuoles and were more spindle-shaped than control or smo...
Origin of the hemagglutinin on A/Equine/Johannesburg/86 (H3N8): the first known equine influenza outbreak in South Africa. A severe influenza outbreak occurred in horses in South Africa in 1986. The causative agent was identified as an influenza virus [A/Equine/Johannesburg/86 (H3N8)]. Antigenic analyses of the hemagglutinin (HA) with ferret antisera and monoclonal antibodies showed that the Eq/Johannesburg/86 virus is similar to recent equine H3 viruses. The nucleotide sequence analysis on the HA genes of Eq/Johannesburg/86 and other equine H3 influenza viruses, together with the epidemiological data, clearly demonstrated that the Eq/Johannesburg/86 virus was derived from a virus that had been circulating in hors...
[The effect of a single dose of dexamethasone on the production of superoxide anion and on the chemotaxis of blood polynuclear neutrophils in the horse]. Chemotaxis and superoxide anion production of neutrophils in healthy horses were investigated before and 8 h after, a single injection of dexamethasone at a dose of 0.045 mg/kg. Chemotaxis was studied by the technique of migration under agarose and superoxyde production was measured by ferricytochrome c reduction. Superoxide anion production was not changed, but the chemotactic index, with zymosan activated horse serum, was increased. The FMLP chemoattractant effect, at 10(-4) M, was slightly enhanced.
In vivo activation of equine eosinophils and neutrophils by experimental Strongylus vulgaris infections. Eosinophils and neutrophils from ponies with Strongylus vulgaris-induced eosinophilia (eosinophilic ponies; activated eosinophils and neutrophils) were assayed in vitro for chemotactic and chemokinetic responses to zymosan-activated serum (ZAS) using the filter system in Boyden chambers, for Fc and complement (C) receptors using the EA and EAC-rosette assays, respectively, and for phagocytic and bactericidal activities using opsonized Escherichia coli and the acridine orange method. The responses of activated eosinophils and neutrophils in the above assays were compared with those of eosinophi...
Equine neutrophil locomotion in response to Streptococcus zooepidemicus. The neutrophil is involved in the defence of the mare's uterus against micro-organisms. The ability of Streptococcus zooepidemicus and its growth products to induce shape changes or directional locomotion (chemotaxis) of equine neutrophils was investigated; no effect was found.
Opsonins in uterine washings influencing in vitro activity of equine neutrophils. Uterine washings were found to promote neutrophil mediated killing of Streptococcus zooepidemicus. Depletion of complement and/or specific antibody from the washings significantly reduced bactericidal activity. Phagocytosis of yeast by uterine washings was complement dependent. Inhibition of the classical pathway significantly reduced opsonic activity indicating that, in addition to direct activation via the alternate pathway, antibody may also be involved in yeast phagocytosis.
Production of monovalent anti-Bothrops asper antivenom: development of immune response in horses and neutralizing ability. A monovalent antivenom was produced by immunizing two horses with venom of the pit viper Bothrops asper (Ophidia: Viperidae). Although development of the immune response against four toxic and enzymatic activities of the venom was similar in both horses during the first two thirds of the immunization schedule, antibody response in one of the horses reached much higher levels in the last part of the immunization. Immunoelectrophoretic analysis indicates that there were precipitating antibodies in the sera of these horses during all the stages of immunization. However, immunoprecipitation did no...
Endotoxin-induced procoagulant activity in equine peripheral blood monocytes. Increasing evidence has demonstrated the importance of monocyte procoagulant activity (PCA) in the pathogenesis of coagulopathies in a variety of diseases. Because endotoxin precipitated coagulopathies are common sequelae to intestinal ischemia/endotoxemia in the equine species, we investigated the ability of equine peripheral blood monocytes to express PCA. Monocytes isolated from five healthy adult horses were incubated in vitro with Escherichia coli endotoxin (10 micrograms), and the PCA was measured by the ability of cellular lysates to accelerate the clotting times of equine plasma in a m...
Chemotactic and chemokinetic activity of Streptococcus faecalis culture supernatant for equine neutrophils. Although equine neutrophils did not respond towards formylated methionyl peptides, Streptococcus faecalis culture supernatant caused an in vitro stimulation of equine neutrophil motility when measured by an under-agarose assay. The migration of neutrophils towards the culture supernatant increased sigmoidally with the logarithmic concentration of the culture supernatant in the chemoattractant wells. The streptococcal culture supernatant was chemokinetic because it stimulated the random motility of the phagocytes. Because granulocytes migrated further towards the supernatant than could be expla...
The hypersensitivity of horses to culicoides bites in british columbia. Culicoides hypersensitivity is a chronic, recurrent, seasonal dermatitis of horses that has a worldwide distribution, but has only recently been reported in Canada. It is characterized by intense pruritus resulting in lesions associated with self-induced trauma.A survey of veterinarians and horse-owners in British Columbia showed no differences in susceptibility due to the sex, color, breed, or height of the horses. The prevalence of the disease in the 209 horses surveyed was 26%. Horses sharing the same pasture could be unaffected. The disease was reported primarily from southwestern British ...
Chemotactic response of equine polymorphonuclear leucocytes to Streptococcus equi. Streptococcus equi infection in horses is characterised by intense infiltration of lymph nodes by polymorphonuclear leucocytes (PMNs) suggesting a potent chemotactic response to the organism or its products. Equine PMNs were separated using Ficoll-Hypaque medium and used in an assay of chemotaxis under agarose to study the components of S equi involved in this response. Results showed that complement-derived chemotactic factors generated by activation of the alternative complement pathway were important in chemotactic responses to S equi. Both whole bacteria and peptidoglycan preparations were...
Pre-chemotactic and chemotactic properties of uterine fluid from mares with experimentally induced endometritis. Streptococcal endometritis was induced experimentally in pony mares during oestrus. Uterine fluid was collected 30, 60, 120 or 240 minutes later and tested for its effect on the in vitro morphology and chemotaxis of equine neutrophils by two independent methods. The maximal response occurred between 30 and 60 minutes after infection and persisted until 240 minutes. The chemo-attractant contained both heat labile and heat stable components and the latter appeared to be active at low concentrations.
Uterine defense mechanisms in the mare. Uterine defense against infection in the mare has been actively investigated over the past decade. Mechanisms of defense, including the role of immunoglobulins, polymorphonuclear neutrophils, and the physical ability of mares to eliminate bacteria from the uterus, are discussed.
Evaluation of immune complexes and collagen type-specific antibodies in sera and synovial fluids of horses with secondary osteoarthritis. Thirty-one horses with secondary osteoarthritis as a sequel of trauma (chip fractures) or osteochondritis dissecans were screened for immune complexes (IC) and anticollagen antibodies. Eighty-two percent of horses with joint disease had circulating C1q-binding IC; 77% of those horses had IC in synovial fluids of affected joints. Although only a few horses had anticollagen type-II antibodies, anticollagen type-I antibodies were found in sera of 25% of the horses and in 41% of their synovial fluids. This correlated well with the clinical data and suggested that antibodies might have been elicite...
Equine neonatal isoerythrolysis: evidence for prevention by maternal antibodies to the Ca blood group antigen. Foals with the Ca blood group antigen on their RBC were given colostrum with anti-Ca antibodies (6 foals) or colostrum without anti-Ca antibodies (6 foals). The PCV were determined at birth and 2, 4, and 6 days after birth for the foals in each group. Significant differences were not observed for the PCV between the 2 groups, indicating that foals were not adversely affected by ingesting colostrum with the anti-Ca antibody. Standardbred mares without the Aa blood group antigen were evaluated to determine whether production of anti-Ca antibodies influenced production of anti-Aa antibodies. Of 2...
Immune responses are required to terminate viremia in equine infectious anemia lentivirus infection. Six normal and four immunodeficient horses were injected with a cloned variant of equine infectious anemia virus (EIAV). The six normal horses had detectable EIAV in their plasma by 7 days postinjection. During their primary viremic episode, which was accompanied by fever and anemia, maximum titers of EIAV in plasma ranged from 10(3.8) to 10(4.8) 50% tissue culture infective doses per ml. All six normal horses cleared detectable virus from their plasma by 21 to 35 days after injection. Horses with combined immunodeficiency became viremic by 9 days postinjection and also developed anemia. In co...
Factors affecting the composition of mare uterine fluid. The influx of protein and polymorphonuclear leucocytes (PMN) into the uterine lumen was examined at different intervals after intrauterine infusion of fluids. The intrauterine infusion of both phosphate buffered saline (PBS) and a solution of lipopolysaccharide (LPS) derived from Escherichia coli resulted in a biphasic influx of protein in the uterine flushings peaking three and six hours after infusion. LPS infusion caused an additional influx of protein at 24 hours. The initial influx of protein preceded a biphasic influx of PMN which peaked six and 24 hours after both infusions. Uterine flu...
The effect of various antibacterial preparations on the in vitro morphology and chemotactic response of equine neutrophils. Two independent assay systems were used to study the effect of three antibacterial preparations on in vitro morphology and chemotaxis of equine neutrophils. Incubation of neutrophils with high (200 micrograms/ml) and medium (20 micrograms/ml) concentrations of neomycin impaired their response to standard chemoattractants. Trimethoprim/sulfadoxine (0.4/2.0 micrograms/ml-40/200 micrograms/ml) and benzylpenicillin (0.25-25 micrograms/ml) had no effect. Neutrophils collected from geldings 2 and 24 h after neomycin (5 mg/kg) administration had impaired responses to standard chemoattractants. Benzyl...
Endotoxaemia in racehorses following exertion. Endotoxins (lipopolysaccharides-LPS) and anti-endotoxin IgG antibodies were measured in racehorses before and after races of 1,000, 2,000 and 2,800 m. Results show that the mean plasma concentration of endotoxin increased significantly (p less than 0.02) while the anti-LPS IgG concentration decreased significantly (p less than 0.005) in all horses following the races. Pre-race and post-race anti-LPS IgG levels in racing-fit racehorses were significantly higher than in untrained horses (p less than 0.05). The possibility therefore exists that training-induced stress leads to leakage of LPS into...
