Transportation of young beef bulls alters circulating physiological parameters that may be effective biomarkers of stress

Transportation causes stress in cattle that may alter numerous physiological variables with a negative impact on production and health. The objectives of the current study were to investigate the physiological effects of truck transportation and to characterize a pattern of phenotypes in the circulation that may aid in the early identification of stress-susceptible animals that often succumb to severe respiratory disease. Thirty-six young beef bulls (Aberdeen Angus, n = 12; Friesian, n = 12; and Belgian Blue x Friesian, n = 12) were subjected to a 9-h truck transportation by road. Blood (10 mL) was collected at -24, 0, 4.5, 9.75, 14.25, 24, and 48 h relative to the initiation of transportation (0 h). Plasma was collected for the assay of various metabolic, inflammatory, and steroid variables, and total leukocyte counts were determined in whole blood at each time point. Body weight and rectal temperature were recorded at -24, 9.75, and 48 h. Transportation decreased measures of protein metabolism in the plasma, including albumin (P = 0.002), globulin (P < 0.001), urea (P = 0.006), and total protein (P < 0.001), and increased creatine kinase (P < 0.001). The energy substrate beta-hydroxybutyrate was not changed (P = 0.27). Acute phase proteins haptoglobin and fibrinogen were both decreased (P < 0.001), whereas total leukocyte counts were elevated (P = 0.002). Circulating steroid concentrations were altered, because a classical acute increase in plasma cortisol was observed with the onset of transit (P < 0.001), in association with a decrease in dehydroepiandrosterone (P = 0.07), resulting in a profound increase in cortisol:dehydroepiandrosterone ratio (P < 0.001). Plasma testosterone was decreased, whereas plasma progesterone was increased (P < 0.001) in association with the increase in cortisol (P < 0.001). There was also an effect of breed for all variables except plasma urea, creatine kinase, and testosterone, perhaps indicating that a genetic component contributed to the physiological response to transportation stress, although without any clear trend. Taken together, this profile of physiological variables in the circulation of transportation-stressed bulls may aid in the future detection of disease-susceptible cattle after transportation. Further research to validate these potential biomarkers is necessary.     

Innate immune responses of temperamental and calm cattle after transportation

The objective was to investigate measures of cellular innate immune responses among calm and temperamental Brahman bulls in response to handling and transportation. Sixteen Brahman bulls (344 ± 37 d of age; 271.6 ± 45.5 kg BW) classified as either calm (n=8) or temperamental (n=8) were loaded onto a trailer, transported for 4h to a novel facility, rested 16 h overnight, and then were returned to their original facility after a 4h transport. Blood samples were collected immediately prior to (time 0) and at 24, 48, and 96 h after initial loading for analyses of innate immune and blood parameters. Leukocyte counts did not differ (P>0.05) due to temperament before or after transportation, but neutrophil:mononuclear cell ratios were greater in temperamental bulls compared to calm bulls at 24h. At 24h, expression of peripheral neutrophil β(2)-integrin decreased among all bulls compared with 0 h (P<0.01). Temperamental bulls had greater glucose and cortisol than calm bulls (P<0.01) at 48 h; whereas calm bulls had elevated neutrophil L-selectin expression, and phagocytic and oxidative burst activity compared with temperamental bulls (P<0.10) at 48 h. The supernatant collected from endotoxin-stimulated whole blood cultures had greater TNF-α concentrations at 48 h than at the other time points (P<0.05), but no temperament effect was observed (P>0.05). In contrast, 96 h after initial loading the supernatant TNF-α concentrations were lower (P<0.05) among all cattle. Lastly, transportation increased neutrophil phagocytosis, oxidative burst, and cell adhesion molecule expression 96 h post-transportation and the effect was more pronounced among calm bulls. These data suggest that neutrophils from calm bulls are more likely to resist microbial invasion at 96 h after transportation than neutrophils from temperamental bulls.     

Modulation, in vivo and in vitro, of surface expression of CD18 by bovine neutrophils.

A series of experiments was designed to elucidate some of the factors that may influence surface expression of CD18 by bovine neutrophils. Expression of CD18 was determined by immunofluorescence flow cytometry. Neutrophils recovered from the uterus of cows (n = 9) after intrauterine administration of sterile oyster glycogen solution expressed (mean +/- SD) 123 +/- 21% more CD18 than did circulating neutrophils recovered simultaneously from the same cows (P = 0.003). In 8 cows given 20 mg of dexamethasone IM daily for 3 days, expression of CD18 on blood neutrophils was 29.6 +/- 8% less after treatment than before treatment (P = 0.0078). Neutrophils from 12 cows or bulls exposed to phorbol myristate acetate in vitro increased expression of CD18 by 137 +/- 37% (P = 0.0035). Likewise, exposure of neutrophils from 8 cattle to zymosan-activated bovine plasma increased CD18 exposure by 10.6 +/- 3.8% (P = 0.029). These findings indicate that expression of CD18 by bovine neutrophils is a dynamic system, capable of responding to inflammatory stimuli. Inadvertent activation of neutrophils may be responsible for some of the variance in expression observed when examining large groups of cattle for CD18 expression by neutrophils. The ability of bovine neutrophils to respond rapidly to various stimuli by increasing surface expression of CD18 indicates that a pool of intracellular CD18 may be available for inclusion in the plasmalemma, as has been reported for human neutrophils.     

Altered protein expression in neutrophils of calves treated with dexamethasone

The effect of glucocorticoid treatment on protein expression in bovine neutrophils was examined with a proteomic approach to address the mechanisms by which stress alters neutrophil function and predisposes to bacterial pneumonia in cattle. Calves 6 to 8 mo old were treated with dexamethasone (0.1 mg/kg), neutrophils were isolated 24 h later, and whole-cell lysates were examined by 2-dimensional electrophoresis. Differentially expressed protein spots were identified by peptide mass fingerprinting. The antimicrobial protein lactotransferrin was detected at increased amounts in the neutrophils of the dexamethasone-treated calves. Proteins detected at reduced amounts in the neutrophils of the dexamethasone-treated calves included annexin 1, phosphoglycerate mutase, Na(+) - K+ ATPase, and cathelicidin 1. These findings identify glucocorticoid-induced changes in the levels of neutrophil proteins involved in host defense, inflammation, and cellular metabolism and suggest additional mechanisms by which glucocorticoids affect neutrophil function.     

Linoleic acid increases adhesion,chemotaxis, granule release,intracellular calcium mobilisation,MAPK phosphorylation and gene expression in bovine neutrophils

Neutrophils are critical to the innate immune response; therefore, the proper function of neutrophils is critical to avoid the development of certain diseases. Linoleic acid, a polyunsaturated long-chain fatty acid, is one of the most abundant long-chain fatty acids found in the plasma of cows after giving birth. In this study, we evaluated the effects of linoleic acid treatment on bovine neutrophil adhesion, chemotaxis, metalloproteinase (MMP)-9 release, CD11b expression, intracellular calcium mobilisation, mitogen-activating protein kinase (MAPK) phosphorylation and COX-2 and IL-8 expression. Bovine neutrophils isolated from healthy heifers were incubated with different concentrations of linoleic acid, and then neutrophil responses were evaluated. Our results show that the treatment of neutrophils with 100 μM linoleic acid increased their adhesion to the bovine endothelial cell line CPA47. The results of a transwell migration assay revealed that linoleic acid could also promote the chemotaxis of bovine neutrophils. Furthermore, linoleic acid treatment increased MMP-9 activity and CD11b cell surface expression in neutrophils. Fifty and 100 μM linoleic acid also increased intracellular calcium mobilisation in neutrophils loaded with Fluo-4 AM dye. Linoleic acid also rapidly (2–5 min) stimulated the phosphorylation of ERK1/2 and p38 MAPK as evaluated by immunoblot. Finally, COX-2 and IL-8 mRNA expression increased after 2 h of linoleic acid treatment. In conclusion, linoleic acid stimulates adhesion, chemotaxis, granule release and intracellular responses in bovine neutrophils.     

D-lactic acid interferes with the effects of platelet activating factor on bovine neutrophils

D-lactic acidosis occurs in ruminants, such as cattle, with acute ruminal acidosis caused by ingestion of excessive amounts of highly fermentable carbohydrates. Affected animals show clinical signs similar to those of septic shock, as well as acute laminitis and liver abscesses. It has been proposed that the inflammatory response and susceptibility to infection could both be caused by the inhibition of phagocytic mechanisms. To determine the effects of d-lactic acid on bovine neutrophil functions, we pretreated cells with different concentrations of D-lactic acid and measured intracellular pH using 2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein acetoxymethyl ester (BCECF-AM) and calcium flux using FLUO-3 AM-loaded neutrophils. Reactive oxygen species (ROS) production was measured using a luminol chemiluminescence assay, and MMP-9/gelatinase-B granule release was measured by zymography. CD11b and CD62L/l-selectin expression, changes in cell shape, superoxide anion production, phagocytosis of Escherichia coli-Texas red bioparticles, and apoptosis were all measured using flow cytometry. Our results demonstrated that D-lactic acid reduced ROS production, CD11b upregulation and MMP-9 release in bovine neutrophils treated with 100 nM platelet-activating factor (PAF). D-lactic acid induced MMP-9 release and, at higher concentrations, upregulated CD11b expression, decrease L-selectin expression, and induces late apoptosis. We concluded that D-lactic acid can interfere with neutrophil functions induced by PAF, leading to reduced innate immune responses during bacterial infections. Moreover, the increase of MMP-9 release and CD11b expression induced by 10mM D-lactic acid could promote an nonspecific neutrophil-dependent inflammatory reaction in cattle with acute ruminal acidosis.     

Matrix metalloproteinase-9 in laminae of black walnut extract treated horses correlates with neutrophil abundance

We sought to determine whether a correlation exists between neutrophil infiltration and tissue matrix metalloproteinase-9 (MMP-9) content in digital laminae collected during the prodromal and acute phases of laminitis in horses treated with an aqueous black walnut heartwood extract (BWE). Hoof laminar tissue was obtained at the onset of leukopenia and at the onset of clinical signs of lameness from BWE-treated horses and at equivalent times from control horses. Thin sections of laminae were screened for neutrophils by immunohistochemistry with an anti-CD13 monoclonal antibody and extracts of the same tissues were screened for SDS-renaturable and native MMP-9 activities by denaturing and non-denaturing gelatin zymography. Samples were also screened for MMP-2 and MMP-9 gene expression by RT-qPCR. Control laminae were devoid of both MMP-9 and neutrophils, whereas neutrophils and SDS-renaturable MMP-9 activity were detected in laminae from BWE-treated horses and were strongly correlated at the acute stage of the disease at which time laminar MMP-9 gene expression was significantly (15-fold) elevated. In contrast, BWE-treatment did not significantly elevate MMP-2 gene or protein expression in the laminae. Interestingly, MMP-9 that was present in extracts of laminae from BWE-treated horses at both the prodromal and acute stages of the disease was mainly in the zymogen form, suggesting that the accumulation of the MMP did not contribute to pathology during these stages. However, elevated presence of the MMP-9 zymogen in the tissue would predispose it to catastrophic damage should conditions arise that cleave the regulatory propeptide domain.     

Transport stress increases somatic cell counts in milk, and enhances the migration capacity of peripheral blood neutrophils of dairy cows

The present study was designed to determine the effects of physiological stress on milk-somatic cell counts (SCC) and function of bovine peripheral blood leukocytes (PBL). Nine healthy lactating cows were used in the examination. Five cows were transported 100 km for 4 hr (transported group; TG), and 4 cows were penned (non-transported group; NTG). Blood and milk samples were collected at 0, 2, and 4 hr after loading, and at 2 hr, and 1, 2, 3, and 6 days after unloading. The following activities were measured: adhesion receptor (CD 18 and L-selectin) expression of neutrophils and monocytes, migration capacity and percentage of apoptotic cells of neutrophils, serum soluble L-selectin (sL-selectin), plasma cortisol, and SCC. A significant increase in plasma cortisol and milk SCC was observed in TG. Leukocytosis, derived from neutrophils was recorded in TG, and was indicated by apoptotic measurement as an increase of young cells from the marginal pool. Increased migration and decreased surface expression of both L-selectin and CD 18 in neutrophils were observed after transportation. Elevated serum sL-selectin was also noted as a result of transportation. The present study indicated that transport stress modulates peripheral blood neutrophil function, particularly enhancing migration capacity, and causes diapedesis across the mammary epithelium. Increased milk SCC in transported cattle might be due to these phenomena, and severe physiological stress may bring about an increase in SCC in milk.     

Involvement of TNF-α and MAPK pathway in the intramammary MMP-9 release via degranulation of cow neutrophils during acute mammary gland involution

Neutrophil-derived MMP-9 activity is regulated more promptly and efficiently at the level of degranulation than at other levels of regulation. In human neutrophils, degranulation is one of the earliest responses to TNF-α stimulation, which involves protein kinase C and mitogen-activating protein kinase (MAPK) pathways. The level of MMP-9 in mammary secretion of cows increases drastically following milk-stasis, which is partially explained by increases of both neutrophil infiltration and neutrophil degranulation per se. Since MMP-9 represents one of the major remodeling capacities in the mammary gland of cows during early dry period, the current study attempted to explore the involved intracellular mechanisms in the up-regulated MMP-9 secretion. We repeatedly measured on the somatic cells of mammary secretion along the early dry period of cows the expression of TNF-α protein and the phosphorylation of p38 MAPK, ERK, and JNK. Also, cultures of bovine peripheral neutrophils were conducted to examine the mode of short-term MMP-9 secretion in response to TNF-α stimulation and the blocking effects of TNF-α antibody and inhibitors of MAPK pathways. Ex vivo measurements show that conventional cow milk has fully transformed into a neutrophil-abundant, lactoferrin-rich, and high-MMP-9 mammary secretion by d 7 in milk-stasis. No significant (P>0.05) change, however, was found in the expression of TNF-α or the phosphorylation extent of MAPK pathway intermediates on the somatic cells of mammary secretion during the first 3 weeks in milk-stasis. In vitro studies indicate linear increase of short-term MMP-9 release in response to TNF-α stimulation in dosages between 0.1 and 10 ng/ml. In the presence of preparations of d 7-dry secretion of cows, the short-term release of MMP-9 from bovine peripheral neutrophils was significantly (P<0.05) blocked by inhibitor of p38 MAPK but was significantly (P<0.05) promoted by ERK inhibitor while TNF-α antibody or JNK inhibitor exerted no effect. In conclusion, the current ex vivo measurements suggest no apparent association of TNF-α and MAPK pathway with long term intramammary accumulation of MMP-9 during the early dry period of cows, whereas cultures of bovine peripheral neutrophils under a simulated acute involution intramammary environment of cows suggest a role played by TNF-α and MAPK pathways in the short-term MMP-9 release via degranulation.     

The effects of stressful exercise on leukocytes in cattle with experimental pneumonic pasteurellosis

Seven yearling bulls were treated with stressful exercise and intrabronchial Pasteurella haemolytica A1. Group 1 bulls (nos. 1–4) underwent treadmill exercise and, 24 days later, intrabronchial instillation of P. haemolytica A1. Group 2 bulls (nos. 5–7) underwent treadmill exercise, followed 30 min later by intrabronchial P. haemolytica A1. Blood lactic acid values were raised (p<0.05) by treadmill exercise only, but plasma cortisol was raised (p<0.05) by treadmill exercise and by P. haemolytica A1 infection. Neutrophils in bronchoalveolar lavage (BAL) differed from control values 24 h after treadmill exercise, and 1 h and 4 h after P. haemolytica A1 infection.Respiratory disease was more severe and the gross lung lesions were larger in group 2 bulls than in group 1 bulls. P. haemolytica A1 was recovered from the livers, spleens and mesenteric lymph nodes of group 2 but not group 1 bulls, suggesting that group 2 bulls had experienced bacteraemia. Decreased neutrophils in BAL fluid from group 2 bulls at 1 h and 4 h after infection suggests that exercise transiently inhibited neutrophil egress from the blood to the alveoli; BAL neutrophils peaked at 1 h and 4 h after infection in group 1 bulls but declined at 24 h. We conclude that group 2 bulls were made more susceptible to experimental pneumonic pasteurellosis by stressful exercise.Abbreviations ADCC antibody dependent, cell-mediated cytotoxicity - AM alveolar macrophages - BAL bronchoalveolar lavage - CFU conlony-forming units     

Migration of fish leucocytes in vitro: the effect of factors which may be involved in mediating inflammation

Plaice (Pleuronectes platessa L.) neutrophils were isolated from the kidney on a discontinuous Percoll gradient and from the peritoneal cavity at the peak of a glycogen-elicited inflammatory response. The migratory ability of neutrophils was assessed using a 48-well microchemotaxis chamber, with an incubation of 1.5 h at 12 degrees C. The two neutrophil populations showed different responses to N-formylmethionyl-leucyl-phenylalanine (FMLP). Whereas kidney neutrophils only showed a significant enhancement of migration at 10(-7) M, inflammatory neutrophils exhibited a bimodal response, with one peak of migratory activity at 10(-9) M and a second at greater than 10(-6) M. Kidney neutrophils showed a consistent response with various concentrations of a 24 h culture supernatant of Vibrio alginolyticus. In every case increased migration was observed with 5-, 10- and 100-fold dilutions, with the latter two conditions producing a significant enhancement (p less than 0.01 and p less than 0.05 respectively). The undiluted and 2-fold diluted supernatant caused a decreased cell migration compared with control values. The supernatant from kidney neutrophils cultured with serum-opsonized, heat-killed V. alginolyticus produced greater migratory activity than neutrophils or the treated bacteria incubated alone (the controls). In each case, the enhanced activity of the supernatant was detectable by 1 h of incubation. By 4 h, the activity of the neutrophil/bacteria supernatant was significantly higher than that of the controls (p less than 0.01), but by 24 h had fallen to control levels. There was no evidence for a chemotactic response with FMLP, the bacterial supernatant or the neutrophil-derived factor and the responses were therefore assumed to be chemokinetic.     

Reproductive criteria of beef bulls during and after exposure to increased ambient temperature

Sixteen yearling Angus bulls were randomly assigned to one of two temperature-controlled chambers to determine the effects of elevated ambient temperature on body functions and semen characteristics. After 8 wk adjustment at 23 C, eight heat-stressed bulls were exposed to 35 +/- 1 C for 8 h and 31 +/- 1 C for 16 h during each 24-h period, and eight control bulls were maintained at 23 +/- 1 C for 8 wk. Then all bulls were exposed to 23 C for 8 wk. Bulls were fed so that both control and stressed bulls gained at similar rates (.58 kg/d). Semen was collected with an artificial vagina twice weekly before, during and after heat stress. During treatment, the respiratory rate of stressed bulls was greater (P less than .001) than that of control bulls (54.2 +/- 1.5, 29.9 +/- 1.5 breaths/min, respectively). Rectal temperatures were increased (P less than .01) from 38.2 +/- .1 to 38.7 +/- .1 C and water consumption was increased by 35% in stressed bulls when compared with controls. Semen volume was not altered by treatment, but percentage of motile sperm decreased (P less than .01) in stressed bulls by 2 wk after the start of heat treatment. Sperm motility of stressed bulls returned to normal values 8 wk after the end of heat treatment. Similarly, the percentage of aged acrosomes on sperm from stressed bulls increased (P less than .01) by the second week of treatment and remained greater than that of controls throughout the stress period.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of supplemental lactoferrin on serum lactoferrin and IgG concentrations and neutrophil oxidative metabolism in Holstein calves

Lactoferrin (LF) is an iron-binding protein present in both colostrum and secondary granules of polymorphonuclear neutrophils (PMNs). We hypothesized that supplemental LF enhances neutrophil function in neonatal calves. Newborn calves were assigned to receive colostrum (C), colostrum + LF (CLF, 1 g/kg), or milk replacer + LF (MRLF, 1 g/kg). Serum (LF and IgG) and whole blood (neutrophil isolation) samples were obtained prior to treatment (day 0) and at 24 hours and 9 days of age. Serum IgG concentrations (mean +/- SD) in C, CLF, and MRLF calves at 24 hours were 1,911 +/- 994 mg/dL, 2,181 +/- 625 mg/dL, and 0 mg/ dL, respectively. Serum LF concentrations in C, CLF, and MRLF calves on day 0 were 324 +/- 334 ng/mL (range 0-863 ng/mL), 135 +/- 158 ng/mL (range 0-429 ng/mL), and 318 +/- 337 ng/mL (range 0-964 ng/mL), respectively. LF concentrations in C, CLF, and MRLF calves at 24 hours were significantly higher (P < .05), at 1,564 +/- 1,114 ng/mL (range 335-3,628 ng/mL, 2,237 +/- 936 ng/mL (range 31-3,287 ng/mL), and 3,189 +/- 926 ng/mL (range 1,736-4,120 ng/mL), respectively. Cytochrome c reduction in opsonized zymosan-treated or phorbol ester-treated cells was not significantly affected by supplemental LF provided at birth. Oral LF is absorbed in calves but does not alter PMN superoxide production and does not alter IgG absorption.     

Responses of horses to trailer design, duration, and floor area during commercial transportation to slaughter

Nine trailer loads of horses (n = 306) transported to slaughter facilities with distances ranging 596 to 2,496 km were studied to characterize the type of horses used in commercial markets and the physiological responses and number of injuries due to transportation under summer environmental conditions. Slaughter horse candidates were middle-aged (11.4+/-.4 yr), possessed moderately fleshy body condition, weighed 432+/-3.3 kg, and were of Quarter Horse or Thoroughbred breeding. The mean weight loss during commercial transport was 4%. The percentage of injured horses was greater (P < .05) for two-tiered "pot-belly" (29.2%) compared with straight-deck (8.0%) trailers; however, the stress indicators of cortisol and neutrophil:lymphocyte ratio and rectal temperature showed greater (P < .05) responses following transport in straight-deck trailers. As trip duration increased from 5 h 45 min to 30 h, muscle fatigue (lactate concentration) and dehydration (hematocrit and total protein concentration) were the major physiological considerations, especially in durations over 27 h. The percentage of horses injured was less (P < .05) in trailers with 1.14 to 1.31 m2 of floor area per horse than in trailers with 1.40 to 1.54 m2 of floor area per horse. However, most physiological responses (white blood cell count, total protein concentration, and neutrophil:lymphocyte ratio) to transportation were less (P < .05) in horses provided with the greater floor area.     

Genetic Variation in Bovine Neutrophil Sensitivity to Glucocorticoid Challenge

Blood neutrophils use CD62L and CD18 adhesion molecules to contact and migrate rapidly through blood vessels in defense against infections in underlying tissues. Previous work showed that glucocorticoid hormones repress expression of CD62L and CD18, causing neutrophilia and increased mastitis susceptibility in dairy cows. The aim of this study was to determine whether bovine neutrophil sensitivity to glucocorticoids exhibits genetic variability. Test animals included 60 pedigreed Holstein bulls treated on 3 consecutive days with a synthetic glucocorticoid (dexamethasone) and five untreated control bulls. Five indicator traits of neutrophil glucocorticoid sensitivity were monitored, including circulating neutrophil counts and two measures on each of CD62L and CD18 expression. Random regression models with treatment-specific serial correlation were used to estimate genetic and non-genetic sources of variation before, during and after glucocorticoid administration. Significant genetic variation was observed for neutrophil CD18 expression, with longitudinal heritability estimates ranging from 0.10 to 0.54 and influenced by dexamethasone. Significant genetic variation was also observed for blood neutrophil counts (heritability estimates ranging from 0.11 to 0.24) but was not influenced by dexamethasone administration. Estimated genetic correlations between circulating neutrophil counts and various indicators of CD62L and CD18 expression were large and negative (-0.44 to - 0.78). These results imply significant genetic variability and pleiotropic effects for neutrophil traits that are important for stress-induced disease susceptibility in dairy cattle and might be exploited by genetic selection.     

Neutrophil function in septic dogs

BACKGROUND: Leukocytes appear to enter a hypo-inflammatory state in human patients with a severe bacterial infection, whereas, in swine, intra-abdominal sepsis produces an initial increase and subsequent decrease in neutrophil Fc receptor mediated phagocytosis. HYPOTHESIS: Impaired neutrophil function (hypo-inflammatory state) develops in dogs with sepsis. ANIMALS: Thirteen adult client-owned dogs that developed clinical signs consistent with sepsis were assessed for evidence of neutrophil dysfunction. These results were compared with those of 12 healthy dogs. METHODS: Flow cytometry combined with the appropriate fluorescent markers allowed for quantification of the phagolysosomal oxidative burst after Fc receptor-mediated phagocytosis of immune complexes, neutrophil phagocytosis of opsonized Escherichia coli, and the intracellular concentration of reduced glutathione as a measure of oxidative stress. RESULTS: The phagolysosomal oxidative burst after Fc receptor-mediated phagocytosis was significantly lower in neutrophils from septic dogs (mean fluorescence intensity +/- standard deviation; 118 +/- 13 and 165 +/- 27 for septic and control dogs, respectively, p = 0.001), although the phagocytosis of opsonized E. coli was significantly increased (155 +/- 74 and 77 +/- 44 for septic and control dogs, respectively, p = 0.004). Intracellular reduced glutathione was not significantly different in neutrophils from septic and healthy control dogs. CONCLUSIONS: An important component of neutrophil function is decreased in septic dogs. The diminished oxidative burst after Fc receptor-mediated phagocytosis in neutrophils from septic dogs could hinder the ability of the innate immune system to clear bacterial infections or it might help protect these patients from the systemic consequences of infection.     

Evaluation of granulocyte transfusion in healthy neonatal pony foals

Granulocyte transfusions (GT), 0.98 X 10(9) neutrophils/kg of body weight, were performed on 7 healthy pony foals between 2 and 7 days old. The mean neutrophil count of the foals was significantly (P less than 0.05) greater than base line (4,830 +/- 1,260/microliter) 1 hour after GT (8,870 +/- 3,350/microliter) and was similar to base line by 15 to 18 hours after GT (6,550 +/- 2,310/microliter). Leukocyte concentrates (LC) used for GT were harvested from clinically normal adult horses by continuous-flow centrifugation leukapheresis (CL), 3 to 6 hours after hydrocortisone sodium succinate was administered to increase the blood neutrophil count. The mean neutrophil count of the LC used for GT was 68,050 +/- 13,990/microliter, and the mean LC volume was 377.4 +/- 79.2 ml (14.82 +/- 3.54 ml/kg). The mean time required to collect the LC used for GT was 232.1 +/- 73.4 minutes. Neutrophils from LC had significantly reduced in vitro stimulated migration to zymosan-activated serum, when compared with peripheral blood neutrophils of the donors (P less than 0.05). Neutrophil phagocytosis and bactericidal capacity were not significantly changed in LC. Mean neutrophil migration indices were not significantly different in foals after GT. Mild depression and transient diarrhea was noticed in 1 foal 30 minutes after the start of the GT. The donor of LC for this foal and 1 other donor experienced depression, piloerection, and muscle tremors during CL, indicating that complement had been activated. Problems were eliminated by the use of new disposable plastic materials for blood processing in each CL procedure.