T cells are a type of lymphocyte that play a significant role in the adaptive immune system of horses. They are involved in identifying and responding to pathogens, such as viruses and bacteria, by recognizing specific antigens. T cells can be categorized into various subsets, including helper T cells (CD4+), cytotoxic T cells (CD8+), and regulatory T cells, each with specific functions in immune regulation and response. The study of T cells in horses encompasses their development, activation, and the mechanisms by which they mediate immune responses. This research area includes investigations into how T cells contribute to equine health, their response to vaccinations, and their involvement in immune-mediated diseases. This page compiles peer-reviewed research studies and scholarly articles that explore the biology, function, and clinical relevance of T cells in equine immunology.
Wagner B, Burton A, Ainsworth D.Cytokines produced by T helper (Th) cells are important in orchestrating the immune response during health and disease. Recent reports indicated that cytokine mRNA expression in foals is often quantitatively lower than that of adult horses suggesting that foal T cells are not fully mature. Here, peripheral blood mononuclear cells from foals and adult horses were stimulated with phorbol 12-myristate 13-acetate and analyzed for intracellular interferon-gamma (IFN-gamma), interleukin-4 (IL-4) and IL-10 production, representing the Th1, Th2 and regulatory TR1 cell phenotypes respectively, by flow ...
Klukowska-Rötzler J, Marti E, Bugno M, Leeb T, Janda J.Thymic stromal lymphopoietin (TSLP) is a novel cytokine that plays a central role in T helper 2 (Th2) cell differentiation and allergic inflammation. It is predominantly expressed by epithelial cells, and its expression is increased in patients with atopic dermatitis and asthma. Mice overexpressing TSLP in the skin develop allergic dermatitis and mice overexpressing TSLP in lungs develop asthma-like disease. However, it is not known whether TSLP plays an important role in equine allergies. Therefore, we cloned and sequenced the complete translated region of equine TSLP gene and measured its ex...
Go YY, Zhang J, Timoney PJ, Cook RF, Horohov DW, Balasuriya UB.Extensive cell culture passage of the virulent Bucyrus (VB) strain of equine arteritis virus (EAV) to produce the modified live virus (MLV) vaccine strain has altered its tropism for equine CD3(+) T lymphocytes and CD14(+) monocytes. The VB strain primarily infects CD14(+) monocytes and a small subpopulation of CD3(+) T lymphocytes (predominantly CD4(+) T lymphocytes), as determined by dual-color flow cytometry. In contrast, the MLV vaccine strain has a significantly reduced ability to infect CD14(+) monocytes and has lost its capability to infect CD3(+) T lymphocytes. Using a panel of five re...
Krakowski L, Krawczyk CH, Wrona Z, Dabrowski R, Jarosz Ł.The objective of the present study was to analyse the immune status of mares in the early stages of pregnancy and mares which experienced early embryonic death (EED). Forty-eight fertile purebred Arabian mares were used for the study. The mares were divided into two groups. Group I was the control group composed of 32 mares in the early stages of a normal pregnancy. Group II was composed of 12 mares which had experienced EED. In both groups, subpopulations of T lymphocytes containing CD2(+), CD4(+) and CD8(+) were characterized using flow cytometry. The percentages of CD3(+) lymphocytes (addin...
Platt R, Sponseller BA, Chiang YW, Roth JA.The cell-mediated immune (CMI) response of foals to virulent equine herpesvirus-1 (EHV-1) infection was evaluated by multi-parameter flow cytometry (FCM). Ten 7-8-month-old EHV-1 seronegative foals were infected intranasally with virulent EHV-1 and 10 foals served as uninfected controls. Blood samples were collected 6 and 7 weeks after infection to test for specific CMI responses to live heterologous EHV-1 recall antigen. The activation markers included major histocompatibility complex class II (MHC II), intracellular interferon gamma (IFN-gamma) and interleukin 4 (IL-4). The results from both...
de Mestre A, Noronha L, Wagner B, Antczak DF.Split immunological tolerance refers to states in which an individual is capable of mounting certain types of immune responses to a particular antigenic challenge, but is tolerant of the same antigen in other compartments of the immune system. This concept is applicable to the immunological relationship between mother and fetus, and particularly relevant in equine pregnancy. In pregnant mares, antibody responses to paternal foreign Major Histocompatibility Complex class I antigens are robust, while anti-paternal cytotoxic T cell responses are diminished compared to those mounted by non-pregnan...
Satué K, Hernández A, Lorente C, O'Connor JE.Assessment of lymphocyte subsets is an effective method for characterizing disorders such as leukemia, lymphomas, autoimmune and infectious diseases. In order to clinically interpret these parameters, normal reference values should be set, estimating age- and gender-related variations. This research aimed to: (1) characterize lymphocyte subpopulations in Andalusian horse, and (2) evaluate age and gender-related variations of lymphocyte subsets. Jugular blood samples were obtained from 159 animals, 77 males and 82 females, belonging to four age groups-1: 1-2 years (N=39; 21 males and 18 females...
Zipplies JK, Hauck SM, Schoeffmann S, Amann B, van der Meijden CH, Stangassinger M, Ueffing M, Deeg CA.Equine recurrent uveitis (ERU) is an incurable disease affecting the inner eye that leads to blindness, through activated T cells that pass the blood-retinal barrier and destroy the retina. Serum markers are a desirable choice for monitoring development of disease, as serum is easy accessible and the markers could serve to predict the beginning of disease or an imminent relapse. Methods: In this study, serum proteomes (depleted of high-abundance serum proteins) of horses with ERU and healthy controls were compared with the 2-D DIGE (two-dimensional gel electrophoresis) technique to identify di...
Schneberger D, Caldwell S, Suri SS, Singh B.Toll-like receptor 9 (TLR9) has been found to be the main receptor to respond to bacterial DNA in a wide variety of species. Recent work has shown that TLR9 is expressed in a diverse set of cells within the lung. However, much of this data has been centered on human and mouse cell culture lines or primary cultures and very little is known of TLR9 expression in intact lung, especially that of the horse. Here we show that TLR9 is expressed in the lungs of horses in a wide variety of cells. In particular, we note expression in pulmonary intravascular macrophages (PIMs), alveolar macrophages, bron...
Tallmadge RL, McLaughlin K, Secor E, Ruano D, Matychak MB, Flaminio MJ.Many features of the equine immune system develop during fetal life, yet the naïve or immature immune state of the neonate renders the foal uniquely susceptible to particular pathogens. RT-PCR and immunohistochemical experiments investigated the progressive expression of developmental B cell markers and immunoglobulins in lymphoid tissues from equine fetus, pre-suckle neonate, foal, and adult horses. Serum IgM, IgG isotype, and IgA concentrations were also quantified in pre-suckle foals and adult horses. The expression of essential B cell genes suggests active development and gene recombinati...
Pargass IS, Wills TB, Davis WC, Wardrop KJ, Alperin DC, Hines SA.There is a distinct age-associated susceptibility of horses to Rhodococcus equi infection. Initial infection is thought to occur in the neonatal and perinatal period, and only foals less than 6 months of age are typically affected. R. equi is closely related and structurally similar to Mycobacterium tuberculosis, and causes similar pathologic lesions. Protective immune responses to M. tuberculosis involve classical major histocompatibility complex (MHC)-restricted T cells that recognize peptide antigen, as well as MHC-independent T cells that recognize mycobacterial lipid antigen presented by ...
Deeg CA.Equine recurrent uveitis (ERU) is a disease with high prevalence and relevance for the equine population, since it results in blindness. Over the last decade, important advancements have been made in our understanding of the underlying immune responses in this disease. ERU is mediated by an autoaggressive Th1 response directed against several retinal proteins. Interphotoreceptor-retinoid binding protein (IRBP) and cellular retinaldehyde-binding protein (CRALBP) are capable to induce ERU-like disease in experimental horses, with the unique possibility to activate relapses in a well-defined mann...
Kelton DR, Holbrook TC, Gilliam LL, Rizzi TE, Brosnahan MM, Confer AW.A 14-year-old spayed American Paint mare was evaluated for mild colic, anorexia, pyrexia, and pancytopenia. Physical examination revealed mild tachycardia, tachypnea, and pale mucous membranes. Serial laboratory analyses revealed progressive pancytopenia, hyperfibrinogenemia, and hyperglobulinemia. A few large atypical cells were observed in peripheral blood smears. Results of tests for equine infectious anemia and antipenicillin antibody were negative. Serum protein electrophoresis indicated a polyclonal gammopathy. Smears of bone marrow aspirates contained hypercellular particles, but cell l...
Lin YZ, Deng XL, Shen N, Lü XL, Zhao LP, Kong XG, Shao YM, Zhou JH.To develop a flow cytometry using (5-carboxyfluorescein diacetate succinmidyl ester, CFSE) to detect the proliferation of specific T lymphocytes from equine infectious anemia virus (EIAV). Methods: Peripheral blood mononuclear cells (PBMC) were isolated, stained with CFSE and incubated with EIAV for 5 days. After interacted with either CD4(+) or CD8(+) antibody, the cells were detected for proliferated population, which contained serially 2-fold reduced CFSE in CD4(+) and CD8(+) T lymphocytes. Results: The concentration of CFSE, and the type, concentration and reaction time of EIAV-specific an...
Witonsky SG, Ellison S, Yang J, Gogal RM, Lawler H, Suzuki Y, Sriranganathan N, Andrews F, Ward D, Lindsay DS.Equine protozoal myeloencephalitis (EPM) due to Sarcocystis neurona infection is 1 of the most common neurologic diseases in horses in the United States. The mechanisms by which most horses resist disease, as well as the possible mechanisms by which the immune system may be suppressed in horses that develop EPM, are not known. Therefore, the objectives of this study were to determine whether horses experimentally infected with S. neurona developed suppressed immune responses. Thirteen horses that were negative for S. neurona antibodies in serum and cerebrospinal fluid (CSF) were randomly assig...
Steinbach F, Bischoff S, Freund H, Metzner-Flemisch S, Ibrahim S, Walter J, Wilke I, Mauel S.Dendritic cells (DCs) are antigen-presenting cells, which are well known for their capacity to stimulate immunity. The ex vivo generation of myeloid DC from monocytes has facilitated the development of DC-vaccination protocols which have been extensively evaluated in tumour immunology and are regarded by some as a gold mine for clinical research. However, there is a considerable amount of work required to overcome the potential risks associated with such therapy. It is therefore mandatory to characterize the system to be applied and to study the reactions, particularly at the level of T cell r...
Deeg CA.Equine recurrent uveitis (ERU) is a wide spread disease of the eye, which is the main cause for blindness in horses worldwide. Meanwhile, ERU is also accepted as the only reliable spontaneous model for human autoimmune uveitis. We identified and characterized novel autoantigens by analyzing the autoantibody-binding pattern from ERU cases to the retinal proteome. Cellular retinaldehyde-binding protein (CRALBP) and malate dehydrogenase (MDH) were detected as novel ERU autoantigens by this approach. B- and T-cell autoreactivity was detected to both autoantigens in ERU cases. The evaluation of the...
Morrison LR, Freel K, Henderson I, Hahn C, Smith SH.Lymphoma (malignant lymphoma, lymphosarcoma) is uncommon in horses in the United Kingdom. This report describes an unusual form of lymphoproliferative disease with features of lymphoma restricted to the central nervous system (CNS) and with no evidence of a primary lesion elsewhere. Immunohistochemical examination defined an overwhelming predominance of T lymphocytes with admixed B lymphocytes and activated macrophages. This case exemplifies the challenges associated with definitive diagnosis of lymphoproliferative disease of the equine CNS.
Adams AA, Breathnach CC, Katepalli MP, Kohler K, Horohov DW.A number of model systems have been employed to investigate age-associated changes in immune function. The purpose of the current study was to characterize senescent T cells and to investigate the inflamm-aging phenomenon both in vitro and in vivo using the old horse as a model. We examined whether decreased T cell proliferation induced by Con A is caused by increased apoptosis. We also utilized intracellular CFSE to analyze changes within each round of cell proliferation, in particular cytokine production. Intracellular staining with flow cytometry, RT-PCR, and ELISA were used to measure pro-...
Lin Y, Deng X, Shen N, Zhao L, Meng Q, Max J, Wang J, Shao Y, Zhou J.The attenuated vaccine of equine infectious anemia virus (EIAV) is the first lentiviral vaccine that provides solid protection against the infection of EIAV virulent strains. Study of the immune response induced by EIAV vaccine is an important approach to understand the immunity to other lentiviruses. IFN-gamma expressed by specifically stimulated lymphocytes is an important indicator for the evaluation of T cell-mediated immunity. A flow cytometry based assay was established in this study to accurately and effectively detect IFN-gamma expression in different subtypes of T lymphocytes in EIAV-...
Mäkinen PE, Archer DC, Baptiste KE, Malbon A, Proudman CJ, Kipar A.Idiopathic focal eosinophilic enteritis (IFEE) and diffuse eosinophilic enteritis (DEE) are primary eosinophilic intestinal conditions without a known cause that are associated with an increasing number of surgical colic cases. Histology may be helpful in defining disease aetiology and pathogenesis. Objective: To characterise further the inflammatory infiltrate in equine IFEE and to compare the condition with DEE. Methods: Twenty-three IFEE cases and 5 DEE cases were examined by light microscopy including immunohistology to identify infiltrating leucocytes. Inflammatory infiltrates in mucosa a...
Lemos KR, Marques LC, Deaquino LP, Alessi AC, Machado RZ.An histochemical and immunohistochemical study was carried out to evaluate the mechanisms of immune response of horses experimentally infected by Trypanosoma evansi. For this purpose the HE histochemical stain and the avidin biotin peroxidase method were used. To determine the presence and immunoreactivity of immune cells we used anti-major histocompatibility complex II antibodies. Cellular infiltration phenotype was characterized with the aid of anti-CD3 antibody for T lymphocytes and by anti-BLA 36 antibodies for B lymphocytes. Macrophages were marked with an antibody against myeloid/histyoc...
Zhang YW, Davis EG, Blecha F, Wilkerson MJ.Innate immunity relies on a series of germline-encoded pattern recognition receptors (PRRs), such as Toll-like receptors (TLRs), to detect conserved microbial components. TLR9 is typically expressed intracellularly in immune cells such as dendritic cells and recognizes unmethylated bacterial or viral cytosine-phosphate-guanine DNA (CpG-DNA). To investigate innate immune responses through TLR9 signaling pathway in horses, we cloned and characterized equine TLR9. Protein sequence analysis shows that equine TLR9 has a typically conserved cytosolic Toll/interleukin-1 receptor (TIR) domain, three l...
El Garch H, Minke JM, Rehder J, Richard S, Edlund Toulemonde C, Dinic S, Andreoni C, Audonnet JC, Nordgren R, Juillard V.Successful vaccination against West Nile virus (WNV) requires induction of both neutralizing antibodies and cell-mediated immune responses. In this study, we have assessed the ability of a recombinant ALVAC-WNV vaccine (RECOMBITEK WNV) to elicit neutralizing antibodies and virus-specific cell-mediated immune responses in horses. In addition, we examined whether prior exposure to ALVAC-WNV vaccine would inhibit B and cell-mediated immune responses against the transgene product upon subsequent booster immunizations with the same vaccine. The results demonstrated that the recombinant ALVAC-WNV va...
van Galen G, Cassart D, Sandersen C, Delguste C, Nollet H, Amory H, Ducatelle R.Polyneuritis equi (PNE) is a rare neurological disease in the horse. Because of the suspicion in PNE of a T-lymphocyte mediated immune response against the myelin, the objective of this study was to determine the composition of the inflammatory infiltrate in the involved nerves of 3 horses with PNE, studied retrospectively. T-lymphocytes were demonstrated in the lesions, which suggests a T-lymphocyte mediated immune response against myelin. In addition, the presence of B-lymphocytes indicated a local production of antibodies. More research, involving a prospective study, is needed to determine...
Rendle DI, Durham AE, Thompson JC, Archer J, Mitchell M, Saunders K, Millere J, Paillot R, Smith KC, Kydd JH.Lymphoid leukaemia (LL) is rare in equids. In man, immunophenotypic classification identifies distinct leukaemic types with different treatment strategies. Improved understanding and classification of equine LL may allow similar advances. Objective: To document the clinical, immunophenotypic and functional characteristics in 6 cases of equine LL of T-cell origin. Methods: The clinical records and pathological findings from 6 cases of equine LL were analysed. Immunohistochemistry to identify T or B lymphocytes was performed on paraffin embedded tissues in 4 cases. Peripheral blood mononuclear c...
Agrícola R, Carvalho H, Barbosa M, Pereira M, Medeiros JA, Ferreira-Dias G.The aim of this study was to evaluate peripheral blood lymphocyte subpopulations, neutrophil phagocytic capacity and proteinogram characteristics in mares, during the last trimester of pregnancy and in postpartum. Measurement of phagocytosis and quantification of T-lymphocyte subsets were done by flow cytometry. Quantification of T-lymphocyte subsets was performed with monoclonal antibodies specific for CD2, CD3, CD4 and CD8 cell markers. Natural killer and B-cell counts were estimated mathematically. Serum proteinogram was obtained by electrophoresis. No significant differences were observed ...
Wagner B, Hillegas JM, Brinker DR, Horohov DW, Antczak DF.Interleukin-10 (IL-10) terminates inflammatory immune responses and inhibits activation and effector functions of T-cells, monocytes, macrophages and dendritic cells. IL-10 has also been found to be a key cytokine expressed by subpopulations of regulatory T-cells. In this report, we describe the generation and characterization of three monoclonal antibodies (mAbs) to equine IL-10. The antibodies were found to be specific for equine IL-10 using different recombinant equine cytokine/IgG fusion proteins. Two of the anti-equine IL-10 mAbs were selected for ELISA to detect secreted IL-10 in superna...
Paillot R, Kydd JH, MacRae S, Minke JM, Hannant D, Daly JM.Equine influenza virus (EIV) is a leading cause of respiratory disease in horses. Equine influenza infection induces a long-term immunity to re-infection. Recent strategies of vaccination aim to mimic this immunity by stimulating both antibody and cellular immune responses. Cell-mediated immunity (CMI) to influenza is well defined in man, but little has been done to characterise the responses in the horse. Additionally, the development of reliable assays for the measurement of equine CMI has lagged behind serological methods and vaccine development. In this study, two methods of measuring EIV-...
Antczak DF.One of the most intriguing and dramatic examples of immunological tolerance is displayed by the mammalian foetal-placental unit, which thrives as a semi-allograft in the mother's uterus during pregnancy. The success of the so-called foetal allograft stands in stark contrast to the failure of most tissue and organ grafts to survive without genetic matching of donor and recipient or drastic immunosuppression of the recipient's immune system. Experiments conducted over the past 60 years have revealed multiple mechanisms that enable the conceptus to avoid immunological detection or destruction. Ma...
Roberto Da Costa RP, Carvalho H, Agrícola R, Alpoim-Moreira J, Martins C, Ferreira-Dias G.The purpose of this study was to evaluate different parameters of the immune status in the mare, during the follicular and the luteal phases of the oestrous cycle, in two consecutive years. Functional competence of peripheral blood neutrophils, such as chemotaxis, phagocytosis and oxidative burst was assessed under physiological cyclic conditions (Exp. I). In the second year of this study (Exp. II), besides peripheral blood neutrophil phagocytosis and oxidative burst analysis, circulating lymphocyte subsets were also characterized. The reproductive status in a total of 17 adult cycling mares w...
Vendrig JC, Coffeng LE, Fink-Gremmels J.Deficient innate and adaptive immune responses cause newborn mammals to be more susceptible to bacterial infections than adult individuals. Toll-like receptors (TLRs) are known to play a pivotal role in bacterial recognition and subsequent immune responses. Several studies have indicated that activation of certain TLRs, in particular TLR-2, can result in suppression of inflammatory pathology. In this study, we isolated peripheral blood mononuclear cells (PBMCs) from adult and newborn horses to investigate the influence of TLR-2 activation on the inflammatory response mediated by TLR-4. Data we...
Poppie MJ, McGuire TC.Combined immunodeficiency (CID), a defect in both B- and T-lymphocytes, was found to occur in 2.3% of 257 foals of Arabian breeding. All affected foals died by 5 months of age. The belief that CID is transmitted as an autosomal recessive genetic defect was supported by results from matings of dams and sires that had previously produced affected foals. Based on a prevalence of 2.3%, the proportion of carriers of the CID trait among the adult population surveyed was estimated to be 25.7%. Recent descriptions of other immunologic defects in foals emphasized the need for careful differential diagn...
Veldman JE, Keuning FJ, Molenaar I.Two times sublethal total body-X-irradiation with weekly local thymus irradiation established a T-cell deprived experimental model in rabbits. Humoral immunity reactions in draining lymph nodes have been analyzed histologically and at the submicroscopical level after challenge with Salmonella Java vaccine, horse spleen ferritin, horse-gamma-globulin, a chemical sensitizer oxazolone (2 phenyl-4-ethoxymethylene-5-oxazolone) and after skin allografting respectively. The time sequence studies in these animals with an 'isolated B-cell system' are compared with similar experiments in normal non-irra...
El-Sheikh Ali H, Scoggin KE, Ruby R, Loynachan A, Boakari Y, Fernandes C, Dini P, Fedorka CE, Loux SC, Esteller-Vico A, Ball BA.Cervical remodeling is a critical component in both term and preterm labor in eutherian mammals. However, the molecular mechanisms underlying cervical remodeling remain poorly understood in the mare. The current study compared the transcriptome of the equine cervix (cervical mucosa (CM) and stroma (CS)) during placentitis (placentitis group, n = 5) and normal prepartum mares (prepartum group, n = 3) to normal pregnant mares (control group, n = 4). Transcriptome analysis identified differentially expressed genes (DEGs) during placentitis (5310 in CM and 907 in CS) and during the normal prepartu...
Fedorka CE, Loux SL, Scoggin KE, Adams AA, Troedsson MHT, Ball BA.The tolerance of pregnancy by the maternal immune system is balanced between recognition and protection. In the human this is controlled by balancing helper T cell populations (Th1, Th2) in addition to immune suppression from the regulatory arm (Tregs), but this has not been evaluated in the horse. RNA sequencing was performed on chorioallantois and endometrium of mares at 120, 180, 300 and 330 days of gestation (n = 4/stage), as well as 45-day chorioallantois (n = 4) and diestrus endometrium (n = 3). Transcripts were selected for relativity to Th1, Th2, or Treg-associated. qPCR an...
Carpenter S, Baker JM, Bacon SJ, Hopman T, Maher J, Ellis SA, Antczak DF.Sequence and functional analyses were undertaken on two cDNAs and a genomic clone encoding horse major histocompatibility complex (MHC) class I molecules. All of the clones were isolated from a single horse that is homozygous for all known horse MHC class I and class II antigens. The two cDNAs (clones 8-9 and 1-29) were isolated from a lymphocyte library and encode polymorphic MHC antigens from two loci. The genomic cosmid clone, isolated from a sperm library, contains the 8-9 gene. All three genes were expressed in mouse L-cells and were recognized by alloantisera and, for the cDNAs, by allor...
Benvegnen J, De Breuyn B, Gerber V, Rottenberg S, Koch C.The aim of the study was to assess the expression of the immune checkpoint inhibitor programmed death-ligand 1 (PD-L1) in equine sarcoids (ES). Programmed death-ligand 1 is expressed by various cancer cells to block T cell-mediated elimination of tumor cells. Antibodies targeting human PD-L1 were tested by immunohistochemistry for their cross-reactivity with equine PD-L1 using formalin-fixed, paraffin-embedded tissues. Our results do not support an important role of PD-L1-mediated immune evasion in ES disease and hence do not offer a rationale for anti-PD-1/PD-L1-based immunotherapy against ES...
de Bruijn CM, Veenman JN, Rutten VP, Teske E, van Nieuwstadt RA, van den Ingh TS.This study documents the clinical, histopathological, immunohistochemical and flow-cytometric findings in five horses with cutaneous non-epidermotropic malignant lymphoma (ML). The median survival time after discovery of the first subcutaneous nodules was 3.8 years (range 2-5 years: n=4). Histologically, the cutaneous ML had a pleiomorphic structure and contained a mixture of large reticulo-endothelial cells, medium-large sized lymphoid cells with a rounded nucleus and small nucleoli, many medium sized lymphoid cells with irregular nuclei, and some small lymphoid cells. Immunohistochemically (...
Science (New York, N.Y.)March 3, 1972
Volume 175, Issue 4025 996-997 doi: 10.1126/science.175.4025.996
Gershon RK, Kondo K.Mice rendered tolerant to sheep red cells and then given normal thymocytes, made no antibody when immunized with these cells. When immunized with horse red blood cells, however, they made significant amounts of noncross-reacting antibody to sheep red blood cells. This suggests that antibody-making precursor cells (B cells) which are nontolerant but nonactivatable by specific antigen, may exist in tolerant hosts.
Wagner B.Host immune analyses require specific reagents to identify cellular and soluble components of the immune system. These immune reagents are often species-specific. For horses, various immunological tools have been developed and tested by different initiatives during the past decades. This article summarizes the development of well characterized monoclonal antibodies (mAbs) for equine immune cells, immunoglobulin isotypes, cytokines, and chemokines.
Hjertner B, Olofsson KM, Lindberg R, Fuxler L, Fossum C.There is accumulating evidence for the involvement of pro-inflammatory cytokines associated with a T helper 17 response in intestinal disorders such as inflammatory bowel disease (IBD) in humans. The involvement of interleukin (IL)-17 or IL-23 in equine IBD has not been studied and most gene expression studies in the equine intestine have been limited to the use of a single non-validated reference gene. In this study, expression of the reference gene candidates β2 microglobulin (β2M), glyceraldehyde 3-phosphate dehydrogenase (GAPDH), histone H2A type 1, hypoxanthine-guanine phosphoribosyltra...
Faleiros RR, Nuovo GJ, Flechtner AD, Belknap JK.There is increasing evidence of involvement of inflammatory cells in acute laminitis. Objective: To immunolocalise monocytes/macrophages and B and T lymphocytes in the laminar tissue of normal horses and those with black walnut extract (BWE)-induced laminitis. Methods: Immunohistochemistry was used in archived laminar tissue samples from 20 horses divided equally into 4 groups: control animals (CON), and those administered BWE at 1.5 h (1.5H DTP group), at the onset of leucopenia (3H DTP group) and at the onset of lameness (LAM group). Antibodies against CD3, CD20 and CD163 were used to recogn...
Kydd JH, Davis-Poynter NJ, Birch J, Hannant D, Minke J, Audonnet JC, Antczak DF, Ellis SA.Equine herpesvirus 1 (EHV-1) causes respiratory and neurological disease and abortion in horses. Animals with high frequencies of cytotoxic T lymphocytes (CTL) show reduced severity of respiratory disease and frequency of abortion, probably by CTL-mediated control of cell-associated viraemia. This study aimed to identify CTL epitopes restricted by selected major histocompatibility complex (MHC) class I alleles expressed in the equine leukocyte antigen (ELA) A3 haplotype. Effector CTL were induced from EHV-1-primed ponies and thoroughbreds with characterized MHC class I haplotypes and screened ...
Wilson AD.Horses are affected by a wide variety of arthropod ectoparasites, ranging from lice which spend their entire life on the host, through ticks which feed over a period of days, to numerous biting insects that only transiently visit the host to feed. The presence of ectoparasites elicits a number of host responses including innate inflammatory responses, adaptive immune reactions and altered behaviour; all of which can reduce the severity of the parasite burden. All of these different responses are linked through immune mechanisms mediated by mast cells and IgE antibodies which have an important ...
Shively MA, Banks KL, Greenlee A, Klevjer-Anderson P.Equine infectious anemia is a chronic disease of horses caused by a nononcogenic retrovirus. Studies were undertaken to determine the types of cells involved in the in vitro lymphoproliferative response to viral antigens and the dynamics of this reaction. It was observed that reactive lymphocytes were present at unpredictable times in the peripheral blood of infected horses. This reaction was shown to be specific for the interaction of equine infectious anemia virus and T lymphocytes. Enriched B-lymphocyte populations did not divide when exposed to equine infectious anemia virus. Macrophages w...
Perryman LE, Wyatt CR, Magnuson NS, Mason PH.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...
Simeonova GP, Krastev SZ, Simeonov RS.The pathogenic mechanism of equine recurrent uveitis (ERU) is still poorly defined and many variations between experimental animal models and spontaneous disease exist. Objective: The aim of our study was to investigate if Th17 cell-mediated response plays role in the pathogenesis of the used experimental model in horses and to reveal its pathological findings. Methods: Experimental uveitis was induced in 6 healthy horses. The concentrations of retinal autoantigen CRALBP and IL-17 were measured using ELISA in aqueous humor and vitreous body of the 12 inflamed eyes as well as in 12 control non-...
Gilger BC, Yang P, Salmon JH, Jaffe GJ, Allen JB.To determine whether a chemokine (RANTES)-like protein expressed by ciliary epithelium plays a role in uveitis. Methods: 3 clinically normal horses intradermal, 5 eyes from 5 horses with recurrent uveitis, and 10 normal eyes from 5 age- and sex-matched horses. Methods: Cross-reactivity and sensitivity of recombinant human (rh)-regulated upon activation, normal T-cell expressed and secreted (RANTES) protein were evaluated in horses by use of intradermal hypersensitivity reactions and a chemotaxis assay. Aqueous humor and ciliary body of eyes from clinically normal horses and horses with uveitis...
Yang J, Ellison S, Gogal R, Norton H, Lindsay DS, Andrews F, Ward D, Witonsky S.Equine protozoal myeloencephalitis (EPM) is one of the most common neurologic diseases of horses in the United States. The primary etiologic agent is Sarcocystis neurona. Currently, there is limited knowledge regarding the protective or pathophysiologic immune response to S. neurona infection or the subsequent development of EPM. The objectives of this study were to determine whether S. neurona infected horses with clinical signs of EPM had altered or suppressed immune responses compared to neurologically normal horses and if blood sample storage would influence these findings. Twenty clinical...
Witonsky SG, Ellison S, Yang J, Gogal RM, Lawler H, Suzuki Y, Sriranganathan N, Andrews F, Ward D, Lindsay DS.Equine protozoal myeloencephalitis (EPM) due to Sarcocystis neurona infection is 1 of the most common neurologic diseases in horses in the United States. The mechanisms by which most horses resist disease, as well as the possible mechanisms by which the immune system may be suppressed in horses that develop EPM, are not known. Therefore, the objectives of this study were to determine whether horses experimentally infected with S. neurona developed suppressed immune responses. Thirteen horses that were negative for S. neurona antibodies in serum and cerebrospinal fluid (CSF) were randomly assig...
Zhang YW, Davis EG, Blecha F, Wilkerson MJ.Innate immunity relies on a series of germline-encoded pattern recognition receptors (PRRs), such as Toll-like receptors (TLRs), to detect conserved microbial components. TLR9 is typically expressed intracellularly in immune cells such as dendritic cells and recognizes unmethylated bacterial or viral cytosine-phosphate-guanine DNA (CpG-DNA). To investigate innate immune responses through TLR9 signaling pathway in horses, we cloned and characterized equine TLR9. Protein sequence analysis shows that equine TLR9 has a typically conserved cytosolic Toll/interleukin-1 receptor (TIR) domain, three l...
Pérez J, Mozos E, Martín MP, Day MJ.The distribution of T (CD3), B (CD79) lymphocytes, immunoglobulin (IgG, IgM and IgA)-producing plasma cells, macrophages (lysozyme, Mac387) and MHC Class II antigen was analysed in the inflammatory infiltrate associated with 19 equine squamous cell carcinomas (SCCs) and six cases of precancerous lesions (actinic keratosis). The SCCs came from the penis (11 cases), conjunctiva (four), skin (two), nasal cavity (one) and oral cavity (one). Seven cases were well-differentiated and 12 moderately differentiated. Nine cases showed no invasion of peritumoral deep tissues (locally invasive), whereas th...
McKelvie J, Foster AP, Cunningham FM, Hamblin AS.Circulating lymphocyte numbers are elevated in horses with the allergic skin disease sweet itch and skin lesions are typified by an infiltrate of eosinophils and mononuclear cells, the latter of which have not been fully characterised. The aim of the present study was to characterise the lymphocyte subpopulations in the circulation and skin of ponies with sweet itch by flow cytometry and a newly developed modified alkaline phosphatase immunohistochemical technique. Sweet itch ponies were found to have significantly greater numbers of circulating CD5+ and CD4+ T-lymphocytes than normal animals....
Schrenzel MD, Watson JL, Ferrick DA.Genes encoding the horse (Equus caballus) T-cell receptor beta chain (TCRB) were cloned and characterized. Of 33 cDNA clones isolated from the mesenteric lymph node, 30 had functionally rearranged gene segments, and three contained germline sequences. Sixteen unique variable segments (TCRBV), 14 joining genes (TCRBJ), and two constant region genes (TCRBC) were identified. Horse TCRBV were grouped into nine families based on similarity to human sequences. TCRBV2 and TCRBV12 were the most commonly represented horse families. Analysis of predicted protein structure revealed the presence of conser...
