Effect of Oestrous Cycle on the Oxidative Burst Activity of Blood Polymorphonuclear Leucocytes in Cows

Blood polymorphonuclear leucocyte (PMN) oxidative burst activity, plasma cortisol levels, and the total and differential white blood cells counts (WBC) of six cycled dairy cows were evaluated for a period of 24 days, three times a week; on Mondays, Wednesdays and Fridays. The PMN oxidative burst was indirectly evaluated by flow cytometry, measuring the intracellular oxidation of 2′,7′‐dichlorofluorescein diacetate to 2′,7′ dichlorofluorescein (DCF) by H₂O₂‐production. Results are pre‐sented as the mean fluorescence intensity (MFI) of DCF. Cow’s oestrous cycle was evaluated by following the plasma progesterone levels using a radioimmunoassay method. Levels of cortisol in the plasma were measured using a fluorimetric method. The oxidative burst activity of PMN, represented a maximum value (MFI = 117.6 ± 7.4) during the oestrous period. A fall was then observed, in which a steady state was observed during the lutheinic phase of the oestrous cycle, reaching the minimum value [MFI = 73.2 ± 11.2 (p ≤ 0.01)] on the days +8, +9 and +10. No significant variations were observed in the levels of cortisol, or in total and differential WBC, during the whole period. Nevertheless, as far as cortisol levels were concerned, a trend analogous to that of the oxidative burst activity was observed. Our results demonstrated that the oestrous cycle might influence directly, or indirectly, the immune system of cows, by altering the oxidative burst of PMN.     

Phagocytic activity in blood and proliferation of peripheral blood lymphocytes during the perinatal period in primiparous sows

The objective of this study was to determine whether phagocytic activity in blood and proliferation of peripheral blood lymphocytes are impaired during perinatal period. The study comprised 18 primiparous sows (Landras × Large White) free from clinical signs of diseases. During the experiment blood samples were collected three times from each sow. Sampling was performed on three different dates, always from all sows at once. At the first date of sampling sows were 21 ± 3 days before parturition, at the second date ± 1 day around parturition time and at the third date 21 ± 3 days after parturition. Phagocytic activity of monocytes and granulocytes was assessed in heparinized whole blood with addition of fluorescein isothiocyanate (FITC)-labelled opsonized bacteria Escherichia coli and the percentage of phagocytes which have ingested bacteria was measured as fluorescence activity by flow cytometry. The percentage of phagocyting monocytes and granulocytes was lowest at parturition (72.6 ± 16.37, 52.4 ± 20.59) and significantly increased within the next 21 ± 3 days (86.5 ± 6.16, 69.89 ± 5.80). Similarly, the phytohemagglutinin (PHA) (10 μg/ml) stimulated in vitro lymphocyte response was suppressed by parturition in primiparous sows (p < 0.001).     

Blood and Intrauterine Leukocyte Profile and Function in Dairy Cows that Spontaneously Recovered from Postpartum Endometritis

The profile and function of blood and uterine leukocytes were evaluated in 14 dairy cows that spontaneously recovered from postpartum endometritis (mild, n=6 and heavy, n=8; general health not affected). From a minimum of 2 weeks before parturition until 6 weeks postpartum, blood samples were obtained twice weekly for leukocyte counts and leukogram determination and once weekly for flow cytometry assessment of polimorphonuclear neutrophils (PMN) phagocytic capacity and oxidative burst activity. Uterine fluid‐stained smears, obtained twice weekly from parturition until fluid was present in the uterus, were used for determination of the percentage of PMN, of phagocytizing PMN (phago‐PMN) and of the mean number of phagocyted bacteria per phagocytizing PMN (phagocytic index; PI). Uterine swabs were obtained twice weekly from parturition until 35 days postpartum for bacteriological examination. The time of endometritis diagnosis was similar in cows with mild or heavy endometritis but the latter cows had a significantly longer persistence of the infection and of the isolation of Gram‐negative anaerobes from the uterus. However, the effect of group (mild versus heavy) was not significant for all the blood and uterine parameters analysed. The effect of sampling day (within group effect) was significant (p<0.01 to p<0.00001) for all parameters, except for the blood monocyte count and the blood PMN phagocytic capacity, in which only a tendency for significance was observed (p<0.1). The effect of the interaction group × sampling day was significant only for the blood monocyte count. The phago‐PMN and the PI were significantly correlated (r=0.70, p<0.001). A significant correlation was also observed between the uterine fluid phago‐PMN and the blood PMN oxidative burst activity (r=?0.41, p<0.05). At the spontaneous recovery, the blood PMN oxidative burst activity was significantly higher (p<0.05) and the percentage of intrauterine phago‐PMN and the PI were significantly lower (p<0.001 and p<0.01, respectively) than at diagnosis of endometritis. These results suggest that a decrease in blood PMN oxidative burst activity until the first week postpartum could be associated with an increased susceptibility to early postpartum endometritis. The later increase in this parameter as well as the increase in the intrauterine fluid phago‐PMN and PI, might favour the spontaneous resolution of endometritis.     

Effect of cephapirin and mecillinam on the phagocytic and respiratory burst activity of neutrophil leukocytes isolated from bovine blood

Antimicrobial therapy is the most commonly used treatment of bacterial infections in dairy cows. Polymorphonuclear neutrophil leukocytes (PMN) play an important role in the first line defence against invading bacteria and it is important that the function of PMN is not compromised by antibiotics. We investigated the in vitro effect of cephapirin, a first generation cephalosporin, and mecillinam, an amidinopenicillin with activity against mainly Gram-negative bacteria, on phagocytosis and respiratory burst activity of PMN isolated from bovine blood. After in vitro incubation of PMN with different concentrations of the antibiotics, phagocytosis was evaluated by flow cytometry and respiratory burst activity was evaluated by registration of chemiluminescence (CL) with a luminometer. None of the investigated concentrations of cephapirin and mecillinam had an effect in vitro on phagocytosis of Escherichia coli by PMN. At high concentrations (100 and 1000 μg/mL), cephapirin and mecillinam reduced the respiratory burst activity of PMN. Part of these suppressive effects could be ascribed to oxidant scavenging. Inhibitory effects of cephapirin were stronger than mecillinam. In conclusion, cephapirin and mecillinam did not seem to affect antibacterial activity of PMN isolated from bovine blood in vitro at therapeutic concentrations.     

Diapedesis across mammary epithelium reduces phagocytic and oxidative burst of bovine neutrophils.

The effect of diapedesis on the phagocytic and oxidative burst activity of polymorphonuclear neutrophil (PMN) was examined, using an in vitro cell culture model consisting of a monolayer of primary mammary epithelial cells. Isolated blood PMN from 10 cows were added to the basal side of the epithelial cell monolayer. Diapedesis was induced by the addition of complement factor C5a to the apical side of the monolayer. PMN phagocytosis of Staphylococcus aureus and oxidative burst were measured before diapedesis on PMN that were non-activated and activated by incubation with C5a and on PMN after diapedesis, using flow cytometry. The percentages of PMN fluorescing due to phagocytosis of S. aureus and oxidative burst were reduced by 21.2 and 14.4%, respectively, after diapedesis. Pre-incubation in the presence of C5a had no effect on percentage PMN fluorescing due to phagocytosis or oxidative burst. The capacity for individual migrated PMN to phagocytose S. aureus and to produce an oxidative burst, as measured by the intensity of fluorescence, decreased by 34.2 and 30.3%. Activation of PMN with C5a increased intensity due to the oxidative burst, but had no effect on intensity due to phagocytosis. These data show that PMN diapedesis across mammary epithelium results in decreased phagocytosis and oxidative burst of the PMN.     

Immunoenhancing effect of trans-10, cis-12 conjugated linoleic acid on the phagocytic capacity and oxidative burst activity of canine peripheral blood phagocytes

The effect of trans-10, cis-12 conjugated linoleic acid (t10c12-CLA) on the phagocytic capacity and oxidative burst activity (OBA) of canine peripheral blood phagocytes was examined. t10c12-CLA did not directly affect the phagocytic capacity and OBA of peripheral blood mononuclear cells (PBMC), monocytes or polymorphonuclear cells (PMN). However, the phagocytic capacity of PMN and monocytes was enhanced by the culture supernatant from t10c12-CLA-treated PBMC. This supernatant enhanced the latex bead-induced OBA of PMN and monocytes. t10c12-CLA also increased TNF-alpha production by PBMC. Recombinant canine (rc) TNF-alpha also increased the phagocytic capacity and OBA of PMN and monocytes. The ability of the culture supernatant from t10c12-CLA-treated PBMC to stimulate the phagocytic capacity and OBA of phagocytes was inhibited by anti-rcTNF-alpha pAb. These results suggest that t10c12-CLA has an immunoenhancing effect on the phagocytic capacity and OBA of phagocytes, and this effect may be mediated by TNF-alpha released from t10c12-CLA-treated PBMC.     

In Vitro Effect of the Reproductive Hormones on the Oxidative Burst Activity of Polymorphonuclear Leucocytes from Cows: A Flow Cytometric Study

In this study, the effect of reproductive hormones and substances with hormonal activity on the oxidative burst activity of blood polymorphonuclear leucocytes (PMN) high yielding dairy cows was evaluated. Different concentrations of: progesterone, oestradiol 17β, FSH, LH, GnRH, cortisol and PGF2α were incubated in vitro for 4 h with PMN of seven high milk yielding cows, during the period of anoestrous postpartum. Controls were run in parallel in which each hormone was replaced by its solvent. After incubation with hormones the competence of PMN to generate H₂O₂ was monitored by flow cytometry. A down‐regulation on the oxidative burst activity of PMA‐stimulated PMN was observed when cells were incubated with progesterone. Significant (p ≤ 0.001) differences between control and progesterone incubated cells were observed from 6.56 μg/ml. The same predisposition was observed when PMNs were incubated with cortisol. Besides for all concentrations employed, a decrease in the burst activity was observed, only beyond 0.19 mg/ml, statistical differences between the results obtained by the control and the cortisol incubated cells were obtained. Concerning oestradiol 17β, an increase on H₂O₂‐production was observed when PMN were incubated with 15 pg/ml and 45 pg/ml of this steroid (p ≤ 0.05), followed by a depression of the cell’s activity when unphysiological concentrations were employed. Significant (p ≤ 0.05) differences between the obtained with the control and oestradiol 17β incubated cells were observed only in the highest concentration of oestradiol. No statistical differences were observed in the metabolic burst activity of PMN incubated with FSH, GnRH and LH when compared with the results obtained by the control.     

Adhesion molecule and homing receptor expression on blood and milk polymorphonuclear leukocytes during the periparturient period of dairy cattle

Adhesion molecule and homing receptor expression on blood and milk polymorphonuclear leukocytes (PMN) from periparturient dairy cattle was studied. Both percentages and the mean fluorescence intensity (MFI) of PMN expressing CD11a, CD44, CD62L, and LPAM-1 (alpha4 beta7) were evaluated at seven time points during the twenty-one day period post calving. CD11a and CD62L were expressed on 94-100% of PMN in both blood and milk and there were no significant differences in these percentages at any time point. LPAM-1 was expressed on 3-10% of the PMN in the blood and 13-45% in the milk and the percentage of cells expressing LPAM-1 in milk was significantly (P<0.05) greater than in blood at 0, 4, 10, 14, 18 and 21 days after calving. CD44 was expressed on 11-39% of the PMN in blood and 33-69% in the milk and the percentage of cells expressing CD44 in milk was significantly (P<0.05) greater than in blood at all time points. The MFI of CD11a on milk PMN was consistently higher than that of blood PMN throughout the study period and significantly (P<0.05) higher at days 4, 10 and 18 after calving.     

Effect of apoptosis on phagocytosis, respiratory burst and CD18 adhesion receptor expression of bovine neutrophils

Polymorphonuclear neutrophil leukocytes (PMN) play an important role in intramammary defense against infections by Escherichia coli. During mastitis, PMN are confronted with various inflammatory mediators that can modulate their function. In severely diseased cows, increased concentrations of lipopolysaccharide (LPS) and tumor necrosis factor (TNF)-alpha (TNF-alpha) are detected in plasma. Binding of LPS to membrane bound CD14 molecules on monocytes cause release of inflammatory mediators such as TNF-alpha. Because apoptosis of PMN promotes resolution of inflammation and because the LPS and TNF-alpha response in milk and blood is related to the severity of E. coli mastitis, the effect on apoptosis of bovine PMN of increased concentrations LPS and TNF-alpha was studied together with the functionality of apoptotic PMN.Bovine PMN apoptosis, as determined with annexin-V, was induced with high concentrations of either LPS (1000 and 10,000ng/mL) or TNF-alpha (10,000ng/mL) in whole blood following a 6h incubation at 37 degrees C. The apoptosis inducing effect of LPS on PMN was not inhibited following coculture with either anti-bovine TNF-alpha or anti-ovine CD14 monoclonal antibodies. When compared to controls, apoptotic PMN had a similar level of CD18 expression but lacked phagocytic and respiratory burst activity. This is the first study reporting the effects of apoptosis on bovine PMN function. These functional impairments in apoptotic PMN could be important in contributing to the establishment of intramammary infection. Well functioning PMN could finally determine the severity of mastitis following an invasion of bacteria in the mammary gland.     

Cryopreservation of cat testicular tissues: effects of storage temperature, freezing protocols and cryoprotective agents

Cryopreservation of testicular tissue has become a part of gamete preservation in wild animal post-mortem. Using domestic cats as a model for wild felids, this study aimed to (i) investigate the effect of temperature for testicular tissue storage on sperm quality; (ii) compare efficiency of freezing protocols; and (iii) evaluate properties of cryoprotective agents to protect testicular sperm quality. A pair of testes from each cat (n = 9) was cut into four pieces. Three randomly selected pieces were allocated to be (i) fresh controls; (ii) stored at 4 °C for 24 h; and (iii) stored at room temperature (28 °C) for 24 h. After storage, the testicular tissue from each group was cut into 10 small pieces. One piece was assigned to be a control while the others were assigned to three freezing protocols; -80 °C (n = 3), vitrification (n = 3) or two-step freezing (kept above liquid nitrogen vapour for 10 min and submerged in liquid nitrogen) (n = 3). Each of three pieces was frozen using dimethyl sulphoxide (DMSO), ethylene glycol (EG) or DMSO combined with EG. Sperm membrane (SYBR-14/EthD-1) and DNA (acridine orange) integrity were evaluated before and after cryopreservation. The storage of testicular tissue at room temperature decreased the percentage of sperm with intact membrane in fresh tissue (59.5 ± 30.5 vs 87.9 ± 7.0%, p < 0.05). DNA integrity was decreased after 24-h storage either at 4 °C or room temperature (p < 0.05). The two-step freezing resulted in a higher percentage of sperm with intact plasma membrane than the other techniques. Dimethyl sulphoxide, EG and DMSO combined with EG provided similar protection for the sperm membrane and DNA from cryodamages. In conclusion, storage of testicular tissue at 4 °C is necessary to maintain sperm membrane integrity during transportation of tissue for cryopreservation in the freezing laboratory. The results provide information for male gamete rescue in felid particularly when they die unexpectedly in the field where freezing facilities are not well equipped.     

CXCL8((3-73))K11R/G31P antagonizes the neutrophil chemoattractants present in pasteurellosis and mastitis lesions and abrogates neutrophil influx into intradermal endotoxin challenge sites in vivo

Toxic products such as reactive oxygen intermediates released by activated polymorphonuclear neutrophil (PMN) have an important role in the pathophysiology of diseases associated with the deposition of immune complexes (IC) in tissues. IC-induced activation of PMN requires adhesion mediated by integrin adhesion receptors. Of the integrins expressed on PMN, the beta(2) family has been found to be of particular importance for activation of PMN by IC. beta(2) Integrin ligand binding must be activated to enable adhesion to IC. Both activating and inhibitory signals regulate beta(2) integrin ligand avidity and adhesion. The second messenger cyclic adenosine monophosphate (cAMP) has been demonstrated to inhibit the activation of PMN in response to a variety of stimuli. The purpose of this study is to test the hypothesis that cAMP-dependent signals inhibit beta(2) integrin-dependent adhesion of equine PMN to immobilized IC and subsequent adhesion-dependent activation of respiratory burst activity. Treatment of equine PMN with beta(2) adrenergic agonists isoproterenol or clenbuterol, which trigger an increase in intracellular cAMP concentration, inhibited adhesion of equine PMN to IC in a dose dependent manner. Similarly, inhibition of cAMP hydrolysis by the non-specific phosphodiesterase (PDE) inhibitor pentoxifylline and the PDE 4-specific inhibitor rolipram inhibited adhesion of equine PMN to IC. Elevation of intracellular cAMP levels with pentoxifylline, clenbuterol and rolipram also inhibited IC-induced activation of respiratory burst activity in equine PMN. Importantly, co-treatment of equine PMN with rolipram and either beta(2) adrenergic agonist synergistically inhibited both the adhesion of equine PMN to IC as well as the subsequent respiratory burst activity.     

In vitro modulation of caprine monocyte immune functions by ω-3 polyunsaturated fatty acids

The in vitro effects of the ω-3 polyunsaturated fatty acids (PUFAs) eicosapentanoic acid (EPA) and docosahexanoic acid (DHA) on phagocytosis and the extracellular respiratory burst in caprine monocytes were assessed. Blood monocytes incubated with increasing concentrations of EPA or DHA (25–200 μM) demonstrated increased phagocytosis compared to unexposed monocytes. Generation of reactive oxygen species (ROS) was not markedly affected in the presence of EPA and DHA, except at 200 μM, at which concentrations monocyte viability was also reduced.     

Association of parainfluenza-3 virus with bovine macrophages and blood cells: an in vitro study

Bovine blood cells and peritoneal and lung macrophages were exposed in vitro to parainfluenza-3 (PI-3) virus. Residual nonadsorbed PI-3 virus (expressed in percentage of input virus) in the supernate of the various cell fractions 1 hour after incubation at 37 C was as follows: lung macrophages, 11%; peritoneal macrophages, 59%; monocytes, 26%; RBC, 14%; lymphocytes, 28%; and polymorphonuclear cells (PMN), 63%. Lung macrophages, monocytes, lymphocytes, and PMN were monitored over a 72-hour period for hemadsorption of chicken RBC. Hemadsorption increased for lung macrophages and monocytes, whereas it decreased for lymphocytes and PMN. Infective virus could not be recovered from PMN, RBC, lymphocytes, or monocytes for more than 24 hours after PI-3 infection. Recovery of infective PI-3 virus from infected peritoneal and lung macrophages extended over 4 to 8 days, respectively.     

Composition and milk cell characteristics in quarter milk fractions of dairy cows with low cell count

Variation in milk composition and milk polymorphonuclear neutrophil leukocyte (PMN) characteristics and functions among quarter milk fractions were investigated in order to evaluate the optimal fraction for the determination of local immune response. Five fractions were classified during milking: foremilk (I), cisternal milk (II), main milk (III), strippings (IV) and residual milk (V). Somatic cell count (SCC), fat, protein, lactose, sodium, potassium, chloride, polymorphonuclear leukocyte necrosis, apoptosis and oxidative burst were analysed in each fraction. The logSCC and fat concentration were highest in residual milk (P < 0.05), whereas protein and lactose concentration were highest in the earliest fractions (I, II, III) (P < 0.05). Polymorphonuclear neutrophil leukocyte necrosis was lowest in strippings and residual milk (P < 0.05), and PMN apoptosis was lowest in residual milk (P < 0.001). The highest percentage of PMN with oxidative burst was found in residual milk (P < 0.05), and was associated with the highest mean fluorescence intensity (MFI) (P < 0.05). In conclusion, late fractions have more PMN and more active PMN. Nevertheless, it is suggested that each fraction is appropriate in the study of local immune response of the mammary gland, however the fraction used in the study has to be specified.     

Signaling mechanism for equine neutrophil activation by immune complexes

Neutrophils (PMN) are critical host defense cells that have a role in the pathophysiology of a variety of inflammatory diseases, particularly those diseases associated with antigen-antibody immune complexes (IC) deposited in tissues. Activation of PMN by IC is most efficient if the IC are presented immobilized on a surface. Adhesion to the immobilized IC is important for subsequent activation of PMN effector functions, such as generation of reactive oxygen metabolites. Adhesion of human PMN to immobilized IC requires the expression and activation of adhesion receptors called integrins. Of the integrins expressed on PMN, the beta 2 family has been found to be of particular importance for PMN function. The mechanism of beta 2 integrin activation during adhesion to IC has been studied in human PMN, but not in equine PMN. We show here that adhesion of equine PMN to immobilized IC requires beta 2 integrins. Like adhesion, IC-induced respiratory burst activity is dependent on beta 2 integrins. Furthermore, the signaling pathway triggering beta 2 integrin-dependent adhesion of equine PMN to IC and subsequent generation of respiratory burst activity is inhibited by the specific phosphatidylinositol 3-kinase (PI3K) antagonists wortmannin and LY294002 with IC(50) (concentration at which 50% inhibition is achieved) similar to the published values for inhibition of PI3K enzymatic activity. In contrast, PMA-induced activation of beta 2 integrin-dependent adhesion and respiratory burst activity are wortmannin and LY294002 insensitive. These data demonstrate that like in human PMN, IC-induced activation of beta 2 integrins and beta 2 integrin-dependent functions in equine PMN is dependent on PI3K activity.     

Specific antibodies induced by inactivated parapoxvirus ovis potently enhance oxidative burst in canine blood polymorphonuclear leukocytes and monocytes

We have recently shown that inactivated parapoxvirus ovis (iPPVO) effectively stimulates canine blood phagocytes. However, a potential link between innate and adaptive immunity induced by iPPVO remained open. The objective of this study was to define the effects of repeated iPPVO treatment of dogs to evaluate (i) iPPVO-specific antibody production, and (ii) modulation of iPPVO-induced oxidative burst by anti-iPPVO antibodies. Serum analysis of dogs treated repeatedly with iPPVO (Zylexis^®) showed transient production of non-neutralising iPPVO-specific IgG. There was a correlation between iPPVO-specific IgG levels and enhanced oxidative burst rates in vitro upon transfer of immune sera. Even four years after Zylexis^® treatment considerably stronger oxidative burst rates in response to iPPVO were observed in monocytes and PMN, whereas only moderate burst rates were detected in monocytes, but not in PMN, from dogs treated with a placebo. Depletion of serum IgG by protein A-sepharose or by parapoxvirus ovis coupled to sepharose abolished the increase of oxidative burst responses and resulted in burst rates similar to blood leukocytes from control dogs. However, uptake of viral particles was found to be independent of iPPVO-specific IgG and restricted to cells with dendritic and monocytic morphology. These data demonstrate that non-neutralising iPPVO-specific IgG is produced during treatment with Zylexis^®. Moreover, for the first time the interaction of iPPVO with antibodies is shown to enhance oxidative burst.     

Identification of subpopulations of bovine mammary-gland phagocytes and evaluation of sensitivity and specificity of morphologic and functional indicators of bovine mastitis

The number and function of bovine mammary-gland phagocytes were assessed in 8 lactating cows, each tested at least twice within an 8-mo period (total number of observations, 20). Macrophages and polymorphonuclear (PMN) cells were evaluated by conventional cytology, flow cytometry, fluorescent microscopy, and somatic-cell count (SCC). Phagocytosis was evaluated from the uptake of fluorescent beads and expressed as median fluorescence intensity (MFI). Two major subpopulations of phagocytes, of low or high MFI (LFI or HFI), were observed, and there were up to 4 sub-subpopulations within the HFI subpopulation of both macrophages and PMN cells. Fluorescent microscopy identified phagocytes containing up to 4 beads per cell. Cows showing ≤ 72.3% phagocytes by cytology were regarded as non-mastitic (11 observations), and those showing ≥ 80.7% phagocytes were considered to be mastitic (8 observations). Phagocyte MFI was negatively associated with mastitis; that is, the higher the MFI, the lower the SCC. The percentage of HFI PMN cells was the only indicator of mastitis with 100% sensitivity and specificity. Thus, bovine mammary-gland phagocytes consist of several subpopulations of different phagocytic ability, whose assessment more adequately predicts bovine mastitis than do morphologic indicators.     

Influence of naturally acquired feline leukemia virus (FeLV) infection on the phagocytic and respiratory burst activity of neutrophils and monocytes of peripheral blood

The purpose of this study was cytometric evaluation of phagocytic and oxidative burst activity of neutrophils and monocytes in cats naturally infected with FeLV. To conduct the study, the peripheral blood was obtained from 33 cats naturally infected with FeLV. The control group consisted of 30 FeLV-, FIV-, clinically healthy cats. The percentage of phagocytizing neutrophils of peripheral blood was lower in FeLV+ than in FeLV- cats. The percentage of neutrophils and monocytes in which an oxidative burst occurred was lower in FeLV+ than in FeLV-animals. Also an oxidative product formation in neutrophils after E. coli and PMA stimulation was lower in FeLV+ than in FeLV-animals. Obtained results allow to conclude that diminished phagocytic and oxidative burst activity of peripheral blood leukocytes may cause impairment of innate immunity in cats infected with FeLV.     

Oxidative burst and phagocytic activity of phagocytes in canine parvoviral enteritis

Canine parvoviral enteritis (CPE) is a severe disease characterized by systemic inflammation and immunosuppression. The function of circulating phagocytes (neutrophils and monocytes) in affected dogs has not been fully investigated. We characterized the functional capacity of canine phagocytes in CPE by determining their oxidative burst and phagocytic activities using flow cytometry. Blood was collected from 28 dogs with CPE and 11 healthy, age-matched, control dogs. Oxidative burst activity was assessed by stimulating phagocytes with opsonized Escherichia coli or phorbol 12-myristate 13-acetate (PMA) and measuring the percentage of phagocytes producing reactive oxygen species and the magnitude of this production. Phagocytosis was measured by incubating phagocytes with opsonized E. coli and measuring the percentage of phagocytes containing E. coli and the number of bacteria per cell. Complete blood counts and serum C-reactive protein (CRP) concentrations were also determined. Serum CRP concentration was negatively and positively correlated with segmented and band neutrophil concentrations, respectively. Overall, no differences in phagocyte function were found between dogs with CPE and healthy control dogs. However, infected dogs with neutropenia or circulating band neutrophils had decreased PMA-stimulated oxidative burst activity compared to healthy controls. Additionally, CPE dogs with neutropenia or circulating band neutrophils had decreased PMA- and E. coli–stimulated oxidative burst activity and decreased phagocytosis of E. coli compared to CPE dogs without neutropenia or band neutrophils. We conclude that phagocytes have decreased oxidative burst and phagocytic activity in neutropenic CPE dogs and in CPE dogs with circulating band neutrophils.     

Relationship between transportation stress and polymorphonuclear cell functions of bottlenose dolphins, Tursiops truncatus

Dolphins in a captive environment are exposed to various kinds of stresses. Handling and transportation are stressful events for terrestrial mammals, and such stress may affect immune system function and increase susceptibility to infectious diseases. The same phenomenon could occur in dolphins, however, few studies have reported this in dolphins. The objective of this study was to evaluate the relationship between stress and polymorphonuclear (PMN) cell function of dolphins during transportation. Four bottlenose dolphins (Tursiops truncatus) were transported for 6 hr by truck. Serum cortisol levels, leukograms, phagocytosis, and superoxide production of PMN cells were evaluated during handling and transportation compared to resting values. The mean serum cortisol level was significantly increased during handling and transportation (p<0.05) when compared with the resting values. White blood cell (WBC) counts, eosinophil counts, phagocytosis, and superoxide production of PMN cells during handling and transportation stages decreased significantly in comparison with the resting stage (p<0.05). The concentration of serum cortisol was significantly correlated with the results of the WBC counts, eosinophil counts, superoxide production, and phagocytosis (p<0.01, p<0.05, p<0.05, and p<0.001, respectively). The present results indicate that handling and transportation are stressful events for dolphins and could affect their PMN cell functions, thereby leading to the impairment of the immune system.