Phagocytosis in horses refers to the process by which certain cells, known as phagocytes, engulf and digest foreign particles, bacteria, and cellular debris. This cellular mechanism is a part of the innate immune response, helping to protect horses from infections and maintain tissue homeostasis. Key phagocytic cells in horses include neutrophils and macrophages, which are responsible for identifying and eliminating pathogens. Research on phagocytosis in equines explores the efficiency, regulation, and impact of this process on overall health and disease resistance. This page includes peer-reviewed research studies and scholarly articles that investigate the mechanisms, cellular interactions, and implications of phagocytosis in equine immunology.
Madarame H, Takai S, Morisawa N, Fujii M, Hidaka D, Tsubaki S, Hasegawa Y.Rhodococcus equi was isolated from the lungs of six foals with bronchopneumonia. All isolates expressed 15-17-kd antigens by immunoblot analysis and contained a virulence-associated plasmid of 85 or 90 kb. Immunohistochemically, R. equi from all pulmonary lesions showed the expression of 15-17-kd antigens mainly in the phagocytic cells. The specific monoclonal antibody to 15-17-kd antigens of R. equi (MAb 10G5) may be an aid in the diagnosis of R. equi-induced pneumonia.
Theoret CL, Barber SM, Moyana T, Townsend HG, Archer JF.The reparative ability of equine synovium was determined by gross, histological, and ultrastructural examination. The functional potential of the synovium was estimated by examination of synovial cell organelles with transmission electron microscopy. Results from rested and exercised horses were compared to determine the effect of exercise on synovial healing. The response of synovectomized joint to exercise was evaluated with a standardized lameness examination and by gross, histological, and histochemical observations of the articular cartilage. A 7-mm diameter motorized synovial resector wa...
Madigan JE, Valberg SJ, Ragle C, Moody JL.Severe muscle cramping not associated with exercise was observed in 5 horses. Focal muscle groups in various regions underwent intermittent visible contraction. Intermittent prolapse of the third eyelid, sweating, pawing, muscle tremors, and muscle fasciculations also were observed. Clinical signs often were misconstrued as signs of colic. Percussion of muscle induced contraction of muscle groups. Concentrations of serum electrolytes and the acid-base balance were within reference limits, but activities of creatine kinase and aspartate transaminase were moderately high. Muscle biopsy revealed ...
Causey RC, Paccamonti DL, Todd WJ.A total of 22 clinical streptococcal isolates, predominantly Streptococcus zooepidemicus, associated with endometritis in horses were tested for their ability to withstand the natural bactericidal properties of freshly obtained blood. During a 3-hour incubation in blood from a single horse, 8 of these isolates survived and grew, the remainder were killed. To determine whether this ability to grow extended to blood of other horses, 5 of these growing isolates were tested for their ability to grow in the blood of 5 additional horses. The same 5 horses were used for each isolate. The isolates gre...
López Alvarez ML, Bustos Obregón E.The occurrence of phagocytosis of spermatozoa in the epididymis is a controversial issue in male reproductive biology. In this paper we documented, by scanning and electron microscopy, the presence of spermatophages in the lumen of the proximal region of stallion epididymis. Sperm phagocytosis involving the principal cells that line the cauda epididymidis region was also observed. The possible meaning of this process in the removal of damaged, aged or surplus spermatozoa is discussed. These observations were made in samples obtained from random cases, during the course of research work carried...
Johannisson A, Gröndahl G, Demmers S, Jensen-Waern M.Methodological aspects of flow-cytometric evaluation of the phagocytic properties of equine neutrophils were elucidated. The kinetics of attachment and ingestion were studied, and the phagocytic process was more rapidly completed when serum-opsonized yeast cells were used than with use of IgG-opsonized yeast cells. Trypan blue was successfully used to quench fluorescence of non-ingested yeast cells. There were only minor differences in the kinetics of phagocytosis between quenched and unquenched samples, indicating that attachment is rapidly followed by ingestion. Trypan blue quenching caused ...
Mazet I, Pendland J, Boucias D.In this study, the phagocytic ability of Spodoptera exigua hemocytes was compared to horse neutrophils. In vitro assays showed that the insect granulocytes and horse neutrophils actively phagocytose FITC-labeled Paecilomyces farinosus blastospores opsonized with S. exigua hemolymph lectin or horse serum, respectively. Killing of fungal cells by the neutrophils and hemocytes was analyzed under in vitro conditions. Neutrophils reduced the growth of P. farinosus up to 65% whereas no fungicidal activity was observed with hemocyte monolayers. The production of oxygen metabolites by both phagocytic ...
Hondalus MK, Mosser DM.Rhodococcus equi is a facultative intracellular bacterium of macrophages that can cause serious pneumonia in both young horses and immunocompromised people. Essential to understanding rhodococcus pathogenesis is a quantitative documentation of the intracellular events that follow macrophage phagocytosis of the organism. By using a bacterial immunofluorescence staining assay, we verified the intracellular survival and replicative potential of R. equi in both murine peritoneal macrophages and equine alveolar macrophages in vitro. Following an initial lag period of 6 to 12 h, the intracellular nu...
Kluciński W, Winnicka A, Olszewski M, Sikora J, Sitarska E, Niemiałtowski M, Muzylak M, Bylinka G, Wyszyński M.The aim of this study was to compare phagocytic activity of polymorphonuclear cells (PMNs) from the bronchoalveolar lavage of clinically healthy horses and those with severe chronic bronchiolitis. Research was carried out on 28 horses. Chronic inflammation of the lower airways was diagnosed in nine horses. Cells from the respiratory tract were lavaged according to accepted methods. For comparison, PMNs were isolated from peripheral blood of all investigated horses. The phagocytic activity of PMNs was determined in relation to two standard strains of Staphylococcus aureus, Staph, aureus Smith w...
Boschwitz JS, Timoney JF.The antiphagocytic property of equine fibrinogen for Streptococcus equi subsp. equi strain CF32 was examined in vitro. The results of bactericidal assays demonstrated that the presence of fibrinogen enhanced the ability of overnight and early log-phase cultures of strain CF32 to resist killing by equine neutrophils by 12-fold and seven-fold, respectively (p > 0.01). In addition, fibrinogen-coated bacteria treated with fibrinogen specific F(ab')2 fragments were 32% more susceptible to killing by equine neutrophils after opsonization in serum (p > 0.05), indicating that specific epitopes o...
Troedsson MH, Liu IK, Thurmond M.In vitro phagocytosis and chemotaxis of uterine and blood-derived polymorphonuclear neutrophils (PMNs) were compared in mares with different resistance to chronic uterine infection (CUI). Both the primary in vitro function of PMNs and the role of uterine environmental factors on PMN function were investigated. The uteri of mares susceptible to (n = 6) and resistant to CUI (n = 5) were inoculated with 5 x 10(6) Streptococcus zooepidemicus when the mares were in estrus. Uterine secretions in addition to uterine and blood-derived PMNs were sampled at 5 and 24 h later. During a subsequent estrus, ...
Messick JB, Rikihisa Y.The binding, internalization, and proliferation of Ehrlichia risticii in P388D1 cells and equine polymorphonuclear (PMN) leukocytes were studied by immunofluorescent staining and flow cytometric analysis. The binding of ehrlichiae to P388D1 cells at 4 degrees C was dose dependent, and the antigens of bound organisms were susceptible to pronase treatment. Additionally, the binding of ehrlichiae to P388D1 cells was diminished when either P388D1 cells or ehrlichiae were treated with 1% paraformaldehyde for 30 min or 0.25% trypsin for 15 min. These results indicate that the ehrlichial ligand and h...
Atwal OS, Singh B, Staempfli H, Minhas K.The pulmonary intravascular macrophages (PIMs) have been described in several species of animals. This study demonstrates for the first time that the equine lung has PIMs as resident phagocytes in its microvasculature. Their salient features such as globular surface coat, structures of the endocytic pathway, and related cell organelles closely resemble those of the calf, goat, and sheep. The exquisite organization of the coat globules in the form of a linear chain was structurally similar to the lipolytic lipase and the heparin-sensitive globular coat from PIMs of calf, goat, and sheep. Monast...
Crisman MV, Hodgson DR, Bayly WM, Liggitt HD.To determine whether road transport affected pulmonary phagocyte activity, 7 healthy Thoroughbred horses were shipped 1,160 kilometers over 36 hours. Fluid collected by bronchoalveolar lavage (BAL) 12 hours, and 7 and 14 days after transport was analyzed. Results were compared to those from the same horses pre-transport, and 7 non-transported control horses that had BAL performed at the same times as the transported horses. Of cells recovered with BAL the percentage of viable pulmonary alveolar macrophages (PAMs) declined from 90.0 +/- 0.9% pre-transport to 80.0 +/- 3.7% by 2 weeks post transp...
Ishino S, Kumagai K, Kuniyoshi S, Nakazawa M, Matsuda I, Oka M.An immunohistochemical analysis of Rhodococcus equi-induced pneumonia in 10 foals was performed by biotin-streptavidin system. The detection of R. equi was more sensitive in immuno-stain using anti-R. equi serum than in Gram's stain. This bacteria also reacted to anti-BCG serum. Lysozyme and alpha 1-antitrypsin were detectable in macrophages. A particularly intense staining was observed in association with intracellular bacteria. Though a degree of reaction for alpha 1-antichymotrypsin was very low in comparison with lysozyme and alpha 1-antitrypsin, it was also demonstrated in macrophages ing...
Daniel GB, Tucker RL, Buckman T, Daniel SL.Isolated equine granulocytes (WBC), radiolabeled with 99mTc-hexamethylpropyleneamine oxime (99mTc-HMPAO) or 111In-oxine, were evaluated in vitro for their labeling characteristics, viability, and phagocytic function over a 6-hour postlabeling period. Mean +/- SD labeling efficiency for 111In-oxine-WBC was 62.2 +/- 15.3%, which was significantly (P less than 0.001) higher than that for 99mTc-HMPAO-WBC (32.0 +/- 17.0%). In vitro elution of radiolabel from cells was significantly (P less than 0.02) greater for 99mTc-HMPAO-WBC at 0.5, 2, and 4 hours, but was not significantly different from elutio...
Hago BE, Vaughan LC, Plummer JM.A transmission electron microscope study was undertaken to investigate the details of the synovial tendon sheath and bursal lining in horses. The lining cells appeared to be fibroblasts and were buried in a finely granular ground substance. Generally these cells had poor cytoplasmic organelles, sparse short profiles of rough endoplasmic reticulum (RER), few scattered ribosomes and, occasionally, a poorly developed Golgi complex. However, a few lining cells appeared more active, having pronounced RER with dilated cisternane. The surface of the lining cells, particularly those with dilated RER, ...
Wichtel MG, Anderson KL, Johnson TV, Nathan U, Smith L.Functional activities (phagocytosis and killing) of neutrophil leucocytes (NL) and immunoglobulin G concentrations were evaluated in six healthy foals from birth to 6 months of age. Peripheral blood NL were reacted with Streptococcus equisimilis in 20 per cent pooled equine serum for 30, 60 and 90 mins and functional activities of NL were determined using a fluorochrome microassay. Values for foal NL function were compared with those of healthy adult horses (n = 28). Foal neutrophil function was influenced by age. Killing capacity of NL decreased, whereas phagocytic capacity increased, until 1...
Buschmann H, Baumann M.During strenuous exercise of horses that are prepared for international Three-Day-Events a significant decrease in the in vitro killing rate of phagocytosed yeast cells by the blood granulocytes has been observed. Other immunological parameters, such as the phorbolmyristate dependent chemiluminescence in granulocytes and the mitogenic stimulation of blood lymphocytes, remained unchanged.
Bogdan I, Nechifor A, Băşea I, Hruban E.In the Rumanian traditional medicine a transcutaneous implantation of the root of Helleborus purpurascens is used to provoke leucocytosis and neutrophils with the aim to activate chronic diseases for better healing. The skin is perforated with a thick needle (in cattle and horses in the area of the thorax, in sheep and pigs in the ear flap), the transplant is introduced and after 24 hours removed. Though the method is more than 100 years old, it is not reported in the literature. The way of action is unknown. The investigation are performed to show the efficacy of this method of Helleborus-imp...
Foerster RJ, Wolf G.Equine blood polymorphonuclear leukocytes (PMN) were isolated by buffy coat and hypotonic lysis of residual erythrocytes. A highly reproducible method is described for measuring the uptake of opsonized latex microspheres by equine PMN using flowcytometry. The use of cytochalasin D allowed for differentiation of ingested from attached particles. The kinetics of phagocytosis in vitro is shown for different experimental conditions. We developed an assay for evaluation of phagocytic capacity of PMN which allows the assessment of drugs for their influence on phagocytosis in vivo as well as in vitro...
Jain NC, Vegad JL, Kono CS.Equine neutrophil antibody was raised in rabbits inoculated with equine neutrophils isolated to purity greater than 99.0%, using Percoll density-gradient sedimentation. Neutrophil antibody was detected by use of agar gel diffusion, leukoagglutination, indirect immunofluorescence, staphylococcal protein A and streptococcal protein G binding, and phagocytic inhibition techniques. Precipitin lines and leukoagglutination were seen in antiserum dilutions of 1:4 and 1:64, respectively. The specific nature of leukoagglutination was characterized by the formation of rosette-like clumps of neutrophils....
Troedsson M, Concha C, Einarsson S, Holmberg O.From 6 mares with chronic uterine infection, polymorphonuclear neutrophils (PMNs) were obtained from the uterus. In order to recover an adequate number of viable PMNs, 0.1% oyster glycogen was infused into the uterus as a mild irritant 12 h prior to the uterine flushing. Phagocytosis and chemotaxis of the uterine derived PMNs were determined. The supernatant from the uterine flushing was compared with autologous serum for its capacity as an opsonin and chemoattractant. There was a significant increase of both phagocytosis and chemotaxis when autologous serum was used compared with the supernat...
Wong CW, Thompson HL, Thong YH, Thornton JR.Bronchoalveolar lavage samples were collected using a fibreoptic endoscope from horses at specified times before and after single bouts of exercise. Lucigenin-dependent phagocytic chemiluminescence was used to assess the effect of exercise on the alveolar macrophage metabolic activity in response to stimulation by opsonised zymosan. A profound suppressive effect on the chemiluminescence production was present throughout the first three days after exercise. However, the cellular composition of lavage fluids was not altered by the exercise. It is suggested that strenuous exercise may jeopardize ...
Blancquaert AB, Colgan SP, Bruyninckx WJ.To identify the influence of technical factors on the in vitro motility of equine neutrophils towards streptococcus culture supernatant in an under-agarose assay, we studied the changes in eight cell migration parameters. The distances the phagocytes travelled by directed, random and spontaneous migration increased with incubation time, cell concentration and the gelatin and serum contents of the migration plates. The contribution of chemotaxis to the phagocyte migrations, however, decreased simultaneously. The directed and random, though not the spontaneous, migrations of the phagocytes incre...
Morris DD, Harmon BG, Moore JN.A study was performed to determine whether equine antiserum to core lipopolysaccharide (LPS) would enhance phagocytosis of smooth gram-negative (GN) organisms by equine macrophages. Five healthy adult horses (group A) were immunized with a bacterin prepared from the J-5 mutant of Escherichia coli 0111:B4 and Salmonella minnesota R595 to produce antibodies to core LPS. Five horses (group B) served as nonimmunized controls and were given physiologic saline solution instead of the rough mutant bacterin. Serum antibody titers to core LPS and to smooth E coli 0111:B4 were determined by indirect ELI...
Dennis VA, Klei TR, Chapman MR, Jeffers GW.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...
Watson ED.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.
Blancquaert AM, Colgan SP, Bruyninckx WJ.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...
Traub-Dargatz JL, McKinnon AO, Bruyninckx WJ, Thrall MA, Jones RL, Blancquaert AM.Four bronchoalveolar lavages were performed sequentially on 9 control and 8 transport-stressed female horses. Alterations in results of fluid cytologic analyses, microbial content, and phagocyte function of recovered pulmonary macrophages in all horses were determined. Seemingly, absolute and relative increase in the number of inflammatory cells detected in the second bronchoalveolar lavage fluid of control horses was the result of irritation of the first lavage. This increased response was not observed in transport-stressed horses until 5 days after transport (third lavage; 10 days after init...
Anderson NV, DeBowes RM, Nyrop KA, Dayton AD.Twelve horses comprised 3 treatment groups; all horses in 2 of the groups had recently been transported and had clinical and laboratory evidence of respiratory tract infection, with equine influenza type 2 virus being the principal pathogen. Mononuclear phagocytes and other leukocytes from blood, lung, and peritoneal cavity were studied in phagocytosis and erythrocyte-antibody (EA) rosette assays. Total numbers of pulmonary alveolar macrophages were increased over control values in bronchoalveolar lavage (BAL) fluid of group 3 horses after recovery from influenza (P less than 0.02), whereas th...
Allombert J, Vianney A, Laugier C, Petry S, Hébert L.Taylorella equigenitalis is the causative agent of contagious equine metritis, a sexually-transmitted infection of Equidae characterised in infected mares by abundant mucopurulent vaginal discharge and a variable degree of vaginitis, cervicitis or endometritis, usually resulting in temporary infertility. The second species of the Taylorella genus, Taylorella asinigenitalis, is considered non-pathogenic, although mares experimentally infected with this bacterium can develop clinical signs of endometritis. To date, little is understood about the basic molecular virulence and persistence mechanis...
Merritt AM, Cimprich RE, Beech J.Granulomatous enteritis was diagnosed in 9 horses between 1 and 11 years of age. The complaint in all cases was persistent weight loss. Four of the horses had chronic diarrhea. Two consistent diagnostic features were hypoalbuminemia and decreased phagocytic activity of mesothelial cells in the peritoneal fluid. In 2 cases the diagnosis was confirmed by biopsy of the rectal mucosa. Remaining cases were definitively diagnosed by exploratory laparotomy and biopsy or at necropsy.
Mazet I, Pendland J, Boucias D.In this study, the phagocytic ability of Spodoptera exigua hemocytes was compared to horse neutrophils. In vitro assays showed that the insect granulocytes and horse neutrophils actively phagocytose FITC-labeled Paecilomyces farinosus blastospores opsonized with S. exigua hemolymph lectin or horse serum, respectively. Killing of fungal cells by the neutrophils and hemocytes was analyzed under in vitro conditions. Neutrophils reduced the growth of P. farinosus up to 65% whereas no fungicidal activity was observed with hemocyte monolayers. The production of oxygen metabolites by both phagocytic ...
Velineni S, Timoney JF.Streptococcus zooepidemicus causes opportunist respiratory and other infections in the horse. Capsule expression is highly variable and known to affect resistance to phagocytosis. Most clinical isolates producing small, dry colonies at 37°C produce mucoid colonies at temperatures below 35°C. Objective: The aim was to understand the molecular basis of increased capsule expression by equine isolates of S. zooepidemicus at temperatures lower than 35°C. Methods: Cross-sectional observational study. Methods: Capsule production by groups of equine S. zooepidemicus strains was determined at 23, ...
Escribano BM, Castejón FM, Vivo R, Santisteban R, Agüera EI, Rubio MD.Using simple techniques, the neutrophil function, in its phagocytosis and oxidative metabolism stages, was evaluated in horses. This was done before and after moderate exercise at the aerobic-anaerobic threshold (standardized heart rate 150 beats/min and lactate level of 3.07 +/- 0.21 mmol/L). The objective was to determine whether regular training and moderate exercise improved the neutrophil function. A group of 19 horses was used; 11 of these were untrained and the remainder trained for national jumping events. The exercise test consisted of a 5 min trot followed by a 3 min gallop on a long...
Dyer RM, Leid RW.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...
Herbst AC, Reedy SE, Page AE, Horohov DW, Adams AA.Studies investigating age-related changes in the function of monocytes are currently limited for horses. Thus, the main goal of this study was to determine the effect of aging on monocyte phagocytic capacity and pro-inflammatory cytokine responses to bacterial lipopolysaccharide (LPS). A second goal of this work was to examine the effect of aging on the inflammatory cytokine responses to LPS in a whole blood ex vivo model. Seven healthy young adult (4-6 years of age) and seven healthy senior horses (>20 years of age) were enrolled. Phagocytosis of E. coli, and pro-inflammatory cytokine (TNF...
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 ...
Bogdan I, Nechifor A, Băşea I, Hruban E.In the Rumanian traditional medicine a transcutaneous implantation of the root of Helleborus purpurascens is used to provoke leucocytosis and neutrophils with the aim to activate chronic diseases for better healing. The skin is perforated with a thick needle (in cattle and horses in the area of the thorax, in sheep and pigs in the ear flap), the transplant is introduced and after 24 hours removed. Though the method is more than 100 years old, it is not reported in the literature. The way of action is unknown. The investigation are performed to show the efficacy of this method of Helleborus-imp...
Srivastava SK, Barnum DA, Prescott JF.The production of M-protein antigen of Streptococcus equi was studied during in vitro growth in equine blood and in various media. Of 11 S equi strains studied, seven which had initially possessed 0.04 mg or less M-protein per 10 mg of streptococcal cell extract showed an increase in M-protein content after successive culture in heparinised horse blood. Maximum proliferation occurred in Todd-Hewitt (TH) medium with added 0.2 per cent w/v glucose when compared with TH medium alone or TH medium with 2 per cent w/v sucrose, starch, neopeptone or normal horse serum. The M-protein of these strains ...
Morris DD, Strzemienski PJ, Gaulin G, Spencer P.Neutrophil function was evaluated in six clinically normal adult horses, immediately before and 3-6 hours after they were given one dose of hydrocortisone sodium succinate (1 mg/kg body weight). Random migration, stimulated migration to zymosan-activated serum, bacterial phagocytosis and bactericidal capacity of neutrophils were determined in vitro. The mean indices of stimulated migration (net migration and migration ratio) were significantly greater after CS administration (net migration = 62 +/- 23 micron; migration ratio = 11.5 +/- 6.7) than before CS administration (net migration = 44 +/-...
Flaminio MJ, Rush BR, Davis EG, Hennessy K, Shuman W, Wilkerson MJ.This paper describes a method for simultaneously measuring phagocytosis and oxidative burst activity in equine peripheral blood leukocytes by flow cytometry. Opsonized propidium iodide-labelled Staphylococcus aureus (PI-Sa) was used to measure the uptake of bacteria by equine phacocytes and the oxidative burst activity by oxidation of dihydrorhodamine 123. The requirements to achieve optimal activity of phagocytosis and oxidative burst are described. The advantage of the simultaneous technique is that it provides both independent and comparative values for phagocytosis and the oxidative burst,...
Ganjam VK, McLeod C, Klesius PH, Washburn SM, Kwapien R, Brown B, Fazeli MH.The reaction between ovarian hormones and experimental uterine infection (Streptococcus zooepidemicus) was investigated in 3 groups, each containing 6 ovariectomized mares. Group 1 served as controls ('anoestrus'), Group 2 mares were injected with oestrogen ('oestrus') and Group 3 with progesterone ('dioestrus') over a period of 5 weeks. All mares received an intrauterine inoculation of the bacteria 1 week after the start of hormonal treatment, and the results of the challenge were examined by endometrial biopsy and swabs once weekly. At the end of Week 1 no bacteria were recovered from the ma...
Yager JA, Duder CK, Prescott JF, Zink MC.Polymorphonuclear neutrophil leukocytes (PMNL) from 8 healthy foals (2-14 weeks of age) and 2 foals with bacterial pneumonia were separated from whole blood using a 2 step Percoll gradient. Purified PMNL were tested for bactericidal function against Rhodococcus equi and Staphylococcus aureus in the presence of normal horse serum. The percentage uptake after a 15-min pre-incubation of PMNL and bacteria was also calculated. Ultrastructural examination of the interaction of R. equi and normal foal PMNL was performed after 15 min incubation. Results indicated that foal PMNL effectively phagocytose...
Watson ED, Stokes CR, Bourne FJ.Both random and directional migration of blood neutrophils from 9 mares susceptible to persistent endometritis were significantly less (p less than 0.05) than neutrophils from 8 resistant mares. Serum from susceptible mares had significantly more (p less than 0.01) chemotactic activity than serum from resistant mares. Although phagocytosis of yeast blastospores by blood neutrophils from 4 resistant and 3 susceptible mares was similar, uterine neutrophils from susceptible mares were significantly worse (p less than 0.01) at phagocytosis than uterine neutrophils from resistant mares. Uterine was...
Grondin TM, DeWitt SF, Keeton KS.A 9-year-old Arabian mare was evaluated for a 7-day history of malaise. Results of a CBC included a leukocyte concentration within the reference interval (8.4 x 10(3)/microL, reference interval 6.0-14.0 x 10(3)/microL) with an apparent degenerative left shift (segmented neutrophils 1.2 x 10(3)/microL, reference interval 2.5-7.5 x 10(3)/microL; hyposegmented neutrophils 1.8 x 10(3)/microL, reference interval 0.0-0.2 x 10(3)/microL). Serum clinical chemistry results included increased aspartate transaminase, alkaline phosphatase, and gamma-glutamyltransferase activities. A presumptive diagnosis ...
Hansen PJ, Hoggard MP, Rathwell AC.The ability of stallion seminal plasma to modify phagocytosis of spermatozoa and Streptococcus zooepidemicus was examined. Phagocytosis was monitored indirectly as the H2O2 produced by peripheral blood leukocytes after addition of spermatozoa or bacteria. Hydrogen peroxide production after addition of ejaculated spermatozoa was greater (P less than 0.01) than after addition of epididymal sperm. Furthermore, pre-incubation of epididymal sperm with 6.25-50% seminal plasma caused a dose-dependent increase in subsequent H2O2 production by leukocytes (P less than 0.05). In addition, equine serum wa...
Johannisson A, Gröndahl G, Demmers S, Jensen-Waern M.Methodological aspects of flow-cytometric evaluation of the phagocytic properties of equine neutrophils were elucidated. The kinetics of attachment and ingestion were studied, and the phagocytic process was more rapidly completed when serum-opsonized yeast cells were used than with use of IgG-opsonized yeast cells. Trypan blue was successfully used to quench fluorescence of non-ingested yeast cells. There were only minor differences in the kinetics of phagocytosis between quenched and unquenched samples, indicating that attachment is rapidly followed by ingestion. Trypan blue quenching caused ...
Sedgwick AD, Lees P, Dawson J, May SA.The migration of leucocytes to sites of acute and chronic inflammation is an event of central importance to the maintenance of inflammatory processes; extravascular leucocytes are responsible for generating chemical mediators of inflammation and the phagocytosis of particulate matter. They may also be involved in the conversion of acute to chronic inflammatory lesions. Leucocytes are attracted to sites of tissue injury by a range of chemoattractants. This paper describes the development of a method for separating on Percoll gradients purified populations of equine polymorphonuclear and mononuc...
Charbord P, Tippens D, Wight TS, Gown AM, Singer JW.This report describes an IgG1 mouse monoclonal antibody derived after immunization of mice with washed stromal cells from human, long-term bone marrow cultures. The antigen recognized by the antibody (BMS-1) is a carbohydrate-containing prosthetic group that is common to and specific for multiple horse serum proteins. These proteins are avidly ingested by stromal cells and concentrated in endocytic vesicles. Cultured smooth muscle cells took up the horse proteins in a similar manner to marrow stromal cells while cultured marrow fibroblasts, endothelial cells, and hepatoma cells did not. These ...
Zhang H, Zhou T, Su L, Wang H, Zhang B, Su Y.Strangles, which is caused by Streptococcus equi subspecies equi (S. equi), is one of the most prevalent equine infectious diseases with worldwide distribution and leads to serious economic loss in the horse industry. Sortase A (srtA) is a transpeptidase that anchors multiple virulence-associated surface proteins to the cell surface of S. equi. srtA plays a major role in S. equi infection and colonization of the host cell. In this study, we aimed to investigate the effects of srtA mutation on the phagocytic activity and immunogenicity of S. equi. The point-mutated recombinant sortases, includi...
Raidal SL, Bailey GD, Love DN.Flow cytometry was used to assess the phagocytosis of fluorescent-labelled bacteria by equine peripheral blood neutrophils and pulmonary alveolar macrophages. Cell populations were prepared from venous blood following ammonium chloride lysis and from washed bronchoalveolar lavage derived samples. Discrete clusters of cells, corresponding to different leucocyte groups, were readily identified on the basis of differing light scattering properties and could thus be discriminated, negating the need for prior cell separation. Cells able to associate with fluorescent-labelled bacteria (by attachment...
Uhl PB, Amann B, Hauck SM, Deeg CA.Retinal pigment epithelium (RPE) builds the outer blood-retinal barrier of the eye. Since one typical feature of the autoimmune disease, equine recurrent uveitis (ERU), is the breakdown of this barrier, we recently performed comparative analysis of healthy and uveitic RPE. We identified for the first time peripherin 2, which is responsible for visual perception and retina development, to be localized in RPE. The purpose of this study was therefore to validate our findings by characterizing the expression patterns of peripherin 2 in RPE and retina. We also investigated whether peripherin 2 expr...
Traub-Dargatz JL, McKinnon AO, Bruyninckx WJ, Thrall MA, Jones RL, Blancquaert AM.Four bronchoalveolar lavages were performed sequentially on 9 control and 8 transport-stressed female horses. Alterations in results of fluid cytologic analyses, microbial content, and phagocyte function of recovered pulmonary macrophages in all horses were determined. Seemingly, absolute and relative increase in the number of inflammatory cells detected in the second bronchoalveolar lavage fluid of control horses was the result of irritation of the first lavage. This increased response was not observed in transport-stressed horses until 5 days after transport (third lavage; 10 days after init...
Watson ED.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.
Caston SS, Cooper EE, Chandramani-Shivalingappa P, Sponseller BA, Hostetter JM, Sun Y.We investigated CD47 expression in cryopreserved sections of equine cutaneous masses and normal skin. CD47 is a cell surface protein expressed on many cell types and overexpressed in some tumors. Interaction of CD47 and signal regulatory protein-alpha (SIRPα) inhibits phagocytosis by macrophages. Formalin-fixed tissues from horses prospectively enrolled in the study were used to establish a histologic diagnosis. Immunohistochemical assays were performed on cryopreserved tissues using anti-CD47 antibodies or IgG control antibodies. CD47 was not expressed on equine normal skin but positivity to...
López Alvarez ML, Bustos Obregón E.The occurrence of phagocytosis of spermatozoa in the epididymis is a controversial issue in male reproductive biology. In this paper we documented, by scanning and electron microscopy, the presence of spermatophages in the lumen of the proximal region of stallion epididymis. Sperm phagocytosis involving the principal cells that line the cauda epididymidis region was also observed. The possible meaning of this process in the removal of damaged, aged or surplus spermatozoa is discussed. These observations were made in samples obtained from random cases, during the course of research work carried...
Wadsworth AB, Sickles GM.IT HAS BEEN SHOWN THAT THE PNEUMOCOCCUS MULTIPLYING IN THE TISSUES OF THE IMMUNIZED ANIMAL (HORSE) BECOMES ATTENUATED: loses, in varying degrees, its virulence, capacity of capsule formation, susceptibility to phagocytosis, and type specificity. The antigenic activity as an immunizing agent and the production of "soluble specific substance" are also altered. In some instances, the typical pneumococcus characteristics may be quickly restored by one or two passages through a susceptible animal (mouse). In others, virulence is not recovered and the organism remains atypical. Whether these changes...
Buschmann H, Baumann M.During strenuous exercise of horses that are prepared for international Three-Day-Events a significant decrease in the in vitro killing rate of phagocytosed yeast cells by the blood granulocytes has been observed. Other immunological parameters, such as the phorbolmyristate dependent chemiluminescence in granulocytes and the mitogenic stimulation of blood lymphocytes, remained unchanged.
