Topic:Immunology
The equine immune system is a complex network of cells, tissues, and organs that work collaboratively to defend against pathogens and maintain homeostasis. It consists of innate and adaptive components, each with distinct functions and mechanisms. The innate immune system provides the first line of defense through physical barriers, phagocytic cells, and the complement system. The adaptive immune system involves lymphocytes, such as B cells and T cells, which generate specific responses to antigens and provide immunological memory. Research in equine immunology explores the interactions between these components, the impact of genetic and environmental factors on immune function, and the development of vaccines and therapeutics. This page gathers peer-reviewed studies and scholarly articles focusing on the mechanisms, regulation, and clinical applications of the equine immune system in health and disease.
“Haysickness” in Icelandic horses: precipitin tests and other studies. Blood samples were taken from 18 healthy horses (Group A), 15 horses clinically diagnosed to have "haysickness" ("farmer's lung") (Group B), 10 closely related horses (Group C) and 14 inbred horses (Group D). Precipitins in sera were measured by double gel diffusion test against Micropolyspora faeni, Thermoactinomyces vulgaris, Aspergillus fumigatus, Alternaria, Penicillium and Rhizopus species. In Group A, all the horses were precipitin negative except one with a faint reaction to Rhizopus species. In Group B all had precipitin against M faeni. One horse also had precipitins against Rhizopus ...
Allergen-specific ELISA for horse IgE. An enzyme-linked immuno sorbent assay (ELISA) for measuring horse IgE specific to ovalbumin, bencylpenicilloic acid and odinitrocarboxyphenol is described. We used a sandwich type of ELISA by which horse serum was incubated in antigen-coated tubes containing one additional polystyrene ball, followed by rabbit anti horse IgE serum. The tubes were then incubated with biotinylated goat anti rabbit globulin followed by avidin coupled to phosphatase. Endpoint titrations were compared. The ELISA is highly reproducible due to the pretreatment of the polystyrene with glutaraldehyde. The increased anti...
Studies with inactivated equine influenza vaccine. 1. Serological responses of ponies to graded doses of vaccine. Serological responses to three bivalent aqueous equine influenza vaccines of different potency and an adjuvanted bivalent vaccine containing inactivated A/equine/Prague/56 (H7N7) and A/equine/Miami/63 (H3N8) viruses, were examined in seronegative ponies. Potencies of the vaccines, measured by single-radial-diffusion tests, ranged from 4 to 56 micrograms of haemagglutinin (HA) antigen activity/virus strain per dose. Serological responses to vaccination were examined by haemagglutination-inhibition (HI) and single-radial-haemolysis (SRH) tests. Four weeks after a primary dose, HI responses to bo...
Chemiluminescence response of equine alveolar macrophages during stimulation with latex beads, or IgG-opsonized sheep red blood cells. Isolated equine alveolar macrophages were shown to generate a luminol-dependent light response when challenged with a phagocytic stimulus. The chemiluminescent response was not detected with luminol prepared at 1.0 x 10(-5) or 1.0 x 10(-4) molar concentrations, but was readily quantitated when used at a 1.0 x 10(-3) molar concentration. Challenge of the alveolar macrophages with latex particles or with equine IgG-coated sheep red blood cells elicited the luminol-dependent light response, whereas unchallenged equine alveolar macrophages or those challenged with unopsonized erythrocytes failed t...
The isolation and preliminary characterization of a rhabdovirus in Australia related to bovine ephemeral fever virus. CSIRO 368 virus was isolated from blood collected in the Northern Territory from a healthy cow and electron microscope studies showed that the isolate had rhabdovirus morphology. Fluorescent antibody studies and complement fixation tests related the virus to bovine ephemeral fever (BEF) virus. Neutralization tests in both suckling mice and Vero cells showed that the virus was not BEF virus. Antibodies to CSIRO 368 virus were found in cattle sera from northern and eastern Australia and Papua New Guinea. Antibodies were found in 16 out of 45 buffalo, some of which also had antibodies to BEF viru...
Aggregation of equine platelets by PAF (platelet-activating factor). Platelet-activating factor (PAF), a lipid released as a result of immediate allergic reactions from basophils and mast cells as well as by a variety of other cell types and stimuli, is one of the most potent platelet agonists and hypotensive agents known. Equine platelets stimulated over a wide range of PAF concentrations aggregated in a time- and dose-dependent manner. Maximum aggregation was observed at concentrations of PAF as low as 3.58 x 10(-14) M with platelet-rich plasma (PRP) and 3.58 x 10(-16) M with washed platelets. Furthermore, the aggregation observed did not appear to be breed-d...
Surface receptors for IgG and complement on equine alveolar macrophages. Isolated equine alveolar macrophages obtained by bronchopulmonary lavage of four live ponies demonstrated surface receptors for equine IgG, equine IgM, and complement-coated sheep red blood cells, but not equine IgM or complement-coated erythrocytes alone. In addition, demonstration of IgG receptors was found to depend on the level of erythrocyte sensitization and could not be demonstrated by red blood cell rosetting techniques at low levels of sensitization. Demonstration of receptors for equine complement by red cell rosetting techniques required the presence of both IgM antibody and serum d...
Complications associated with immunotherapy of equine phycomycosis. Five horses with pythiosis of the limbs were treated unsuccessfully by surgery or topical application of amphotericin B, or both. Follow-up immunotherapy resulted in 1 horse responding favorably. Three horses were cured of the fungal infection but developed osteitis or deep-seated laminitis, which necessitated their destruction. The remaining horse, which had severe anemia, died before the course of vaccination was completed.
Epidemiological and immunological studies of sweet itch in horses in Israel. A survey of sweet itch in horses in Israel based on a questionnaire to owners reported that 158 of 723 horses (21.8 per cent) had sweet itch lesions. The results indicated that the likelihood of a horse acquiring sweet itch decreased with increasing altitude but no definite association with rainfall zones was evident. Variation in the density of the horse population, however, obscured these observations. In the population surveyed, stallions were more sensitive than mares and pale horses appeared to be less sensitive than dark ones, but the sample size of this latter group was much smaller. In...
Isolation of horse mononuclear cells, especially of monocytes, on Isopaque-Ficoll neutral density gradient. Horse mononuclear cells were separated from whole blood using neutral density gradient centrifugation on Isopaque-Ficoll. The resulting cell suspension was comparable in composition with similarly prepared human and bovine mononuclear cell preparations. The relative concentration of monocytes was increased by the use of a gradient with density lower than that originally proposed by Böyum (Böyum, A. 1968. Scand. J. Clin. Lab. Investig. 21 supple. 97:77-89). Contamination by neutrophils was limited either by using a gradient medium of lower density or by replacing Isopaque-Ficoll by Percoll-0....
Antibody responses of ponies to initial and challenge infections of Strongylus vulgaris. An indirect fluorescent antibody assay (IFA) was developed using Strongylus vulgaris third stage larvae (L3) as antigens. Observations using the IFA indicate that a species-specific antibody response to S. vulgaris L3 develops in S. vulgaris-infected ponies and that some surface L3 antigens are shared by adult worms. Sequential antibody levels against S. vulgaris were measured in strongyle-naive and in immune ponies following initial and challenge infections using the IFA and an indirect hemagglutination assay (IHA). Antibody levels measured by IFA increased faster following initial infections...
Adaptation of human diploid fibroblasts in vitro to serum from different sources. The growth of two human diploid skin fibroblast cell lines, originally grown in medium supplemented with foetal bovine serum and later adapted to medium supplemented with newborn bovine, bovine calf or horse serum, has been studied. Prolonged generation times increased cell volumes and decreased plating efficiencies were observed in cultures grown in newborn bovine, bovine calf or horse serum. In general, the deleterious effects were most severe as a result of growth in bovine calf or horse serum. In the light of the present findings, we believe investigators should exert great caution in swit...
Animal model of human disease. Infantile X-linked agammaglobulinemia. Agammaglobulinemia in horses. This research explores X-linked agammaglobulinemia in horses, a severe immune deficiency found in various horse breeds, leading to clinical signs like pneumonia and arthritis. Lymphoid tissues show an absence of […]
A study on the possible role of chymotrypsin in the aetiology of equine chronic obstructive pulmonary disease (COPD). The chymotrypsin activity of seven batches of Micropolyspora faeni and of five batches of Aspergillus fumigatus culture extracts, prepared for inhalation challenge in horses, was assayed and was found to range between 0.29 and 1.45 units/mg protein and 0.02 and 0.20 units/mg protein respectively. Horses affected with chronic obstructive pulmonary disease (COPD) were challenged with two batches of each antigen which had different chymotrypsin activities and no significant correlations were found between the degree of response to challenge and the chymotrypsin activity of the antigens. Inhalatio...
The equine spleen: an electron microscopic analysis. The capacity of the equine spleen to store and rapidly release as much as half the circulating blood volume after adrenergic stimulation depends upon the size of the spleen, its muscular capsule, and the distinctive structure of its red pulp. The unit, or lobule, of red pulp is a cylinder of pulp spaces organized in a reticular meshwork, supplied by a peripheral ring of arterial capillaries, and drained by a central venule. Reticular cells, which make up the meshwork of the pulp, contain an extraordinarily large complement of microfilaments and intermediate filaments and are richly innervated ...
Experimental Streptococcus equi infection in the horse: correlation with in vivo and in vitro immune responses. Fourteen young outbred horses, divided into 2 groups on the basis of 18- or 24-hour skin-test reactions to Streptococcus equi, were inoculated nasopharyngeally with virulent S equi. Animals (n = 6, group I) with evidence of previous exposure to S equi (positive dermal response and existing serum antibodies), with one exception, developed minimal or no signs of disease after inoculation. In contrast, S equi skin-test negative and seronegative horses (n = 8, group II) developed predictable and severe clinical signs of infection after their inoculation, including shedding of the organism from nas...
Cell-mediated immune response to Babesia equi-transformed lymphoblastoid cells in vitro. The capacity of equine peripheral blood lymphocytes (PBL) to proliferate in the presence of Babesia equi-transformed lymphoblastoid stimulator cells was tested in an autologous as well as in an allogenic one way mixed lymphocyte reaction (MLR). It was found that both autologous and allogeneic responder lymphocytes incorporated high amounts of 3H-thymidine. The incorporation of 3H-thymidine was lower in MLR using as stimulator cells lymphocytes from which the cell line had previously been established, than when using parasitized culture cells as stimulator. Proliferation of PBL was achieved onl...
A reagin-like antibody in horse serum. II. Anti-human IgE induced reversed cutaneous anaphylaxis-like responses in horse skin. Fc specific anti-human IgE serum induced prolonged reversed cutaneous anaphylaxis (RCA)-like reactions in horse skin. Morphologically and histologically, these reactions resembled passively induced late cutaneous anaphylaxis responses in human skin, but differed from reversed passive Arthus responses induced in horse skin using anti-horse IgG serum. The induction of RCA-like responses in horse skin by anti-human IgE indicates shared Fc antigenic determinants on human IgE and a horse homocytotropic or reagin-like antibody.
The genetic control of antibody formation. Studies of the molecular biology of lymphoid cells have markedly increased our understanding of how millions of different antibodies can be synthesized by a single animal. To date, the most detailed understanding has been achieved for the mouse, primarily because of the relatively greater experimental availability of this species. These studies, as well as those involving other species, have shown that the complete genes for antibody polypeptide chains are assembled from disparate genetic elements which are originally widely separated in the genome. The assembly process itself, together with t...
Efficacy of ivermectin in controlling Strongyloides westeri infections in foals. Twenty-eight foals whose dams were treated IM with ivermectin (200 micrograms/kg of body weight) on the day of parturition were compared with 35 foals whose dams were administered only the vehicle. The effect of ivermectin on the vertical transmission of Strongyloides westeri and foal heat diarrhea was determined by a comparison of results obtained in the 2 groups. Foals from treated mares had significantly fewer S westeri eggs per gram of feces from 17 to 28 days postpartum. There were no differences observed in the frequencies of severity of foal heat diarrhea between the treated and control...
Equine complement activation as a mechanism for equine neutrophil migration in Onchocerca cervicalis infections. Extracts of Onchocerca cervicalis, an equine parasite, were incubated with radiolabeled equine neutrophils and neutrophil migration was assessed for factors derived from the parasite itself or for host-derived factors after incubation of these same parasite extracts with equine serum. No stimulus for cell migration was observed in saline extracts of adult worms, uterine microfilariae, or skin microfilariae at any dosage tested. However, after incubation of saline extracts with fresh normal equine sera a marked stimulus for neutrophil migration was observed. Ablation of this biologic activity w...
Further study of the chemical structure of the equine erythrocyte hematoside containing O-acetyl ester. The chemical structure of an equine hematoside, which contained an ester group and comprised 72% of the total erythrocyte gangliosides, was determined by means of nondestructive and destructive procedures. A 400-MHz nuclear magnetic resonance spectrum of the ganglioside in perdeuterodimethyl sulfoxide demonstrated three protons due to a methyl group of an acetyl moiety, as well as amide and anomeric protons which were compatible with those of the ordinary hematoside. The spin decoupling difference spectroscopy of the ganglioside revealed the presence of the following structures. [formula: see ...
Effects of common radioiodination procedures on the binding of glycoproteins to immobilized lectins. Representative glycoproteins including fetuin, protein A, ovalbumin, alpha 1 acid glycoprotein, and the major glycoprotein of equine infectious anemia virus were labelled with 125I by the chloramine-T or Bolton-Hunter procedure and their binding to immobilized Con A or lentil lectin compared to untreated samples of each glycoprotein. Glycoprotein modification was no greater than one substituted residue per protein molecule. Yet the radioiodinated glycoproteins typically displayed only 0-50% of the lectin binding observed with untreated samples. These results indicate that lectin glycoprotein b...