Biomedical subjects

L M Sordillo

Publications and source records attributed to L M Sordillo.

At least 37 records · Page 2Linked to original sources

PubMed1997

Efficacy of a bovine Staphylococcus aureus vaccine using interleukin-2 as an adjuvant.

The purpose of this study was to examine the efficacy of a vaccination protocol using recombinant bovine interleukin-2 (rBoIL-2) as an adjuvant with a Staphylococcus aureus vaccine. Holstein dairy cows were immunized with a S. aureus vaccine in conjunction with either saline solution (n = 3), Freund's incomplete adjuvant (FIA; n = 3) or rBoIL-2 (n = 3). Whey and serum were analysed for antibody titer to specific S. aureus antigens. Isolated blood mononuclear cells (BMC) were examined for their ability to proliferate and to produce interleukin-2 (IL-2) and interferon (IFN) after either mitogenic or antigenic stimulation in vitro. Efficacy of the vaccination protocols was assessed by challenging experimental animals intramammarily with 100 colony forming units of S. aureus. Regardless of treatment, all cows exhibited similar serum antibody titers to S. aureus pseudocapsule. Cows treated with saline exhibited a significant increase in serum alpha-toxin antibody titer when compared to levels observed in FIA and rBoIL-2-treated cows. However, cows receiving rBoIL-2 treatment exhibited significantly higher lacteal pseudocapsule antibody titer compared to the other adjuvant groups. Administration of rBoIL-2 did not enhance BMC proliferative responses to the mitogens concanavalin A (ConA), phytohemagglutinin (PHA), pokeweed mitogen (PWM) or interleukin-2 (IL-2) when compared to FIA or saline treated cows. Although cows receiving rBoIL-2 treatment exhibited enhanced cytokine production upon antigenic stimulation, efficacy of the vaccination protocol was inferior compared to the protection offered by saline treatment.

Adjuvants, Immunologic↗

PubMed1997

Arginine supplementation increases weight gain, depresses antibody production, and alters circulating leukocyte profiles in preruminant calves without affecting plasma growth hormone concentrations.

The hypothesis that dietary L-arginine (L-Arg) supplementation would increase growth hormone (GH) secretion and antibody production in preruminant calves was tested. Sixteen newborn calves were randomly assigned to either Arg+ or Arg- treatment groups. Both groups were fed a single dose of Colostrx within 6 h after birth followed by milk replacer twice daily until weaning. Beginning with the Colostrx feeding, calves in the Arg+ group were supplemented with L-arginine at 500 mg kg x BW(-1) x d(-1), and the Arg- group received equivalent, but unsupplemented, diets. All calves were immunized against keyhole limpet hemocyanin (KLH) on d 4 and received a booster vaccination on d 14. The Arg+ treatment increased (P < .05) plasma L-Arg and urea concentrations an average of 2.8-fold and 26%, respectively, during the 4-wk supplementation period. Average daily gain (ADG) of Arg+ calves was increased (P < .10) during wk 1, 3, and 5 of life. The Arg+ treatment depressed (P < .05) total and KLH-specific IgG concentrations in plasma and caused a decrease (P < .01) in circulating leukocyte numbers. Differential counts revealed that the decrease in circulating leukocyte numbers was due to decreases in absolute numbers of lymphocytes, monocytes, and neutrophils. The Arg+ diet did not affect mean plasma GH concentrations during the first 3 wk of life, but GH mean concentrations were decreased (P < .01) during wk 4 due to depressed (P < .10) pulse amplitudes. The decrease in GH mean concentrations during wk 4 was paralleled by lower (P < .10) plasma IGF binding protein-3 concentrations. These data show that supplementary L-Arg does not increase plasma GH concentrations, but it increases ADG, depresses KLH antibody production, and alters circulating leukocyte populations in preruminant calves.

Aging↗

PubMed1997

Immunobiology of the mammary gland.

The mammary gland is a complex organ that provides neonatal offspring with milk for nourishment and disease resistance. Specific and innate immune factors associated with mammary gland tissues and secretion also play a vital role in protecting the gland from infectious disease. Through genetic selection and technological advances in milk removal, the bovine mammary gland yields for more milk than is needed to nourish the newborn calf. This excess is the basis of the dairy industry. Factors associated with the intense management of dairy cattle can profoundly affect mammary gland immunity and the ability of the host to resist mastitis. Technological advances in immunology have led to the availability of new research tools that can facilitate the study of mammary gland immunity and disease pathogenesis. In recent years, considerable research effort has focused on enhancing the natural defense mechanisms of the mammary gland during periods of heightened susceptibility to disease. This paper provides a comprehensive overview of mammary gland immunity with special emphasis on the bovine system. The underlying mechanisms of disease susceptibility and development of potential immunoregulatory strategies to control mastitis are discussed.

Animals↗

PubMed1997

Concentrations of alpha-Tocopherol after intramammary infusion of Escherichia coli or lipopolysaccharide.

Fifteen Holstein cows were used in a trial involving intramammary challenge to determine the effects of acute clinical mastitis on the concentrations of alpha-tocopherol in milk and plasma and the concentrations of neutrophils in milk and blood. Cows were assigned to one of three experimental groups challenged by intramammary infusion of lipopolysaccharide, Escherichia coli, or sterile phosphate-buffered saline. All quarters infused with lipopolysaccharide or E. coli were diagnosed with clinical mastitis on d 1 and 2 after challenge. Acute inflammation caused by intramammary infusion of lipopolysaccharide or E. coli resulted in increased concentrations of alpha-tocopherol in milk in challenged quarters but had no effect on concentrations of alpha-tocopherol in plasma. Concentrations of alpha-tocopherol in milk and blood neutrophils did not differ among treatment groups. Concentrations of alpha-tocopherol did not differ between milk and blood neutrophils. Approximately 25% of the alpha-tocopherol in milk from glands with clinical mastitis was associated with neutrophils, and < 10% of the alpha-tocopherol in milk from nonmastitic glands was associated with neutrophils. A shift toward sources of alpha-tocopherol other than synthesized milk fat occurred during acute inflammation in the mammary gland.

Animals↗

PubMed1996

Evidence for G-protein-dependent and G-protein-independent activation of phospholipase D in lymphocytes.

Previously we reported that tumor-promoting phorbol esters stimulate phospholipase D (PLD) independent of protein kinase C (PKC) activation in bovine lymph node lymphocytes. (Cao et al., Biochem. Biophys. Res. Commun. 171, 955-962, 1990; 217, 908-915, 1995). In the present study, we examined the effects of prostagladins (PGs), E2, F2 alpha, D2, and H2 on PLD activity as measured by conversion of [1-14C] arachidonic acid-labeled phospholipids into phosphatidylethanol (PEt) in bovine lymph node lymphocytes. Prostaglandins stimulated the formation of PEt at an optimal concentration of 10 microM with relative stimulatory effect on the order of PGE2 > PGF2 alpha > PGH2 > PGD2. The PGE2-stimulated formation of PEt was dose-dependent in the range of 0.1 to 10 microM and was not inhibited by PKC inhibitors staurosporine and K252a. When both PGE2 and 12-0-tetradecanoylphorbol-13-acetate (TPA) were included, their effect on the PLD activation was additive. Furthermore, NaF, a G-protein activator, stimulated the PEt formation. Interestingly, the stimulatory effects of PGE2 and NaF were not additive; however, the formation of PEt by NaF and TPA was additive. These results suggest that similar to TPA, PGs increase PLD activity independent of PKC and the stimulation by PGs and TPA in lymphocytes may involve both G-protein-dependent and G-protein-independent signaling pathways.

Animals↗

PubMed1996

alpha-Tocopherol concentrations in milk and plasma during clinical Escherichia coli mastitis.

Eighteen cows were challenged by intramammary infusion with Escherichia coli 727 to determine the effects of acute clinical mastitis on alpha-tocopherol concentrations in plasma and milk. Cows were fed diets supplemented with 1000 IU of vitamin E/d from calving through the experimental period. At challenge, geometric mean DIM was 33 d. Each mammary quarter was diagnosed with an IMI and clinical mastitis at 24 and 48 h after challenge. The alpha-tocopherol concentrations in milk from challenged quarters were approximately 60% greater by 24 and 48 h after challenge than concentrations at prechallenge and 168 h postchallenge. Plasma alpha-tocopherol concentrations did not change after intramammary challenge. The alpha-tocopherol in plasma and milk was correlated at 48 and 168 h postchallenge but not at prechallenge or 24 h postchallenge. Milk alpha-tocopherol and SCC were correlated positively across all sample periods. Milk fat and milk alpha-tocopherol concentrations were correlated at each sample period except 24 h postchallenge. Increases in milk alpha-tocopherol during clinical mastitis were not correlated to milk production, DMI, or BSA concentration in milk. Changes in milk alpha-tocopherol concentration during clinical mastitis were similar to the dynamics of milk SCC.

Animals↗

PubMed1996

Enhancing bactericidal activity of bovine lymphoid cells during the periparturient period.

The antibacterial activity of bovine lymphocytes was evaluated following in vitro stimulation with interleukin-2. Mononuclear cells were isolated from the blood, lymph node, and mammary parenchymal tissue of four lactating and four periparturient dairy cows. These cells were evaluated for antibacterial activity against Staphylococcus aureus following incubation for 48 h with or without interleukin-2. Cultures stimulated with interleukin-2 had higher bactericidal activity of all three isolated cell populations than did unstimulated cultures, regardless of lactational stage. This observation suggests that this effector function may possibly be activated in vivo and may potentially increase mammary gland resistance to bacterial infections during periods of increased susceptibility. Flow cytometric analysis of the cultured cells revealed that antibacterial effector cells were mainly CD2+ and were depleted of macrophages. Despite shifts in CD4+, CD8+, and gamma delta T lymphocytes during the periparturient period, bactericidal activity was similar among the three cell sources. This similarity suggests that these lymphocyte phenotypes might not be directly responsible for this effector function. Identification of the antibacterial effector phenotype and its mechanism of action may lead to immunoregulatory strategies aimed at enhancing this novel bactericidal function.

Animals↗

PubMed1996

Diminished mammary gland lymphocyte functions parallel shifts in trafficking patterns during the postpartum period.

Once activated, lymphocytes can regulate both specific and nonspecific immune responses. Alterations in lymphocyte function may increase the host's vulnerability to bacterial infections such as mastitis. Susceptibility to mastitis as well as diminished leukocyte functional capabilities have been shown to be influenced by lactational stage. Therefore, the present study characterized the phenotypes and functions of several bovine lymphoid populations at two points in the lactational cycle. Mononuclear cells were isolated from peripheral blood, supramammary lymph nodes, and mammary parenchyma of mid-lactating and postpartum dairy cows. The phenotypic composition, proliferative ability, cytokine secretion, and cytotoxic activity of isolated leukocytes were assessed with respect to lactational stage and tissue source. Lower percentages of T lymphocytes were consistent with diminished mitogen-stimulated proliferation and spontaneous cytotoxic activity by lymphocytes isolated from postpartum compared with mid-lactating animals. Stimulation with interleukin-2 did not enhance the cytotoxic activity or proliferative ability of lymphocytes isolated postpartum to similar levels observed for those isolated from mid-lactating animals. These data indicate that certain diminished lymphocyte functions observed during the postpartum period may result from shifts in leukocyte trafficking patterns.

Animals↗

PubMed1996

Specific immune responses of dairy cattle after primary inoculation with recombinant bovine interferon-gamma as an adjuvant when vaccinating against mastitis.

OBJECTIVE: To examine whether specific immunity in the mammary gland and blood of dairy cattle was enhanced after primary inoculation with a test antigen keyhole limpet hemocyanin (KLH) and recombinant bovine interferon-gamma (rBoIFN-gamma) as an adjuvant. DESIGN: Holstein dairy cows received IM injections of KLH in conjunction with saline solution (n = 4), Freund's incomplete adjuvant (FIA; n = 4), or rBoIFN-gamma (n = 3). Milk and blood samples were collected during a 1-month period and analyzed for KLH antibody content. Isolated blood mononuclear cells were examined for their ability to proliferate and produce interleukin 2 (IL-2) after mitogen and/or KLH stimulation in vitro. The phenotype of isolated blood mononuclear cells also was characterized through flow cytometric analysis. RESULTS: The adjuvant rBoIFN-gamma induced serum KLH antibody titers similar to those induced by administration of FIA. However, FIA induced significantly more KLH antibodies in milk. Administration of rBoIFN-gamma enhanced T-lymphocyte activity, as indicated by the greater expression of high-affinity IL-2 receptors and the increased response to the mitogens concanavalin A, phytohemagglutinin, and IL-2, compared with FIA or saline treatment. Lymphocyte and monocyte movement from the blood also was altered after rBoIFN-gamma treatment, which can have a profound influence on secondary immune responses, such as antibody production. CONCLUSIONS: rBoIFN-gamma may safely enhance specific immunity in the bovine mammary gland and may be an effective adjuvant in mastitis immunization protocols.

Adjuvants, Immunologic↗

PubMed1995

Enhanced production of bovine tumor necrosis factor-alpha during the periparturient period.

This study examined the production of tumor necrosis factor (TNF-alpha) by mononuclear cells isolated from peripheral blood and supramammary lymph nodes of periparturient and mid to late lactating dairy cows. Monocyte-enriched cell populations were stimulated with lipopolysaccharide (LPS) and analyzed for TNF-alpha concentrations. Flow cytometric analysis was performed to determine the frequencies of relevant cell populations. Isolated mononuclear cells from periparturient dairy cows produced significantly higher levels of TNF-alpha than mid to late lactating dairy cows regardless of tissue location. A corresponding increase in the frequency of monocytes also was observed in tissue samples obtained from periparturient animals. The higher proportion of monocytes capable of producing TNF-alpha in the periparturient dairy cow may account for the increased levels of this potent mediator. Within the periparturient period, peripheral blood mononuclear cells were found to produce significantly less TNF-alpha than cells isolated from mammary lymph nodes. However, flow cytometric analysis revealed similar monocyte concentrations in both the peripheral blood and mammary lymph node. This indicates that the differences in cytokine production may be due to variations in monocyte activation state with respect to tissue location. It is possible that greater potential to produce TNF-alpha during the periparturient period may contribute to the severe acute phase response of the mammary gland to coliform infections during this time. Limiting TNF-alpha production by monocytes, particularly within the mammary gland, may reduce the severity of clinical coliform mastitis in periparturient dairy cattle.

Animals↗

PubMed1995

Effects of an Escherichia coli J5 vaccine on mild clinical coliform mastitis.

Efficacy of an Escherichia coli (O111:B4) J5 bacterin was tested in an experimental challenge trial. Nineteen cows were vaccinated with an E. coli J5 bacterin, and 10 cows were injected with a placebo containing adjuvant only. Vaccine and placebo were administered at drying off, 30 d after drying off, and within 48 h after calving. Cows were challenged approximately 30 d after calving by intramammary infusion with a smooth heterologous strain of E. coli previously shown to cause mild clinical mastitis. Vaccination with the J5 bacterin reduced duration of IMI and local signs of clinical mastitis. Concentrations of BSA in milk 24 h after challenge were greater in control cows than in cows vaccinated with J5. The SCC at 7 d postchallenge were greater for cows vaccinated with the placebo than for cows vaccinated with J5. Bacterial counts were lower for cows vaccinated with the placebo than for cows vaccinated with J5 at 3, 6, and 9 h postchallenge. In contrast, cows vaccinated with J5 had lower bacterial counts at 2, 3, and 4 d postchallenge than did cows vaccinated with placebo. Systemic signs of clinical mastitis were relatively mild and similar between treatment groups. Rectal temperature, DMI, and milk production did not differ between control and cows vaccinated with J5 following challenge.

Administration, Topical↗

PubMed1995

Enhanced antigen-specific responses in bovine mammary glands following administration of interleukin-2.

This study examined the feasibility of using interleukin-2 as a vaccine adjuvant to enhance specific immunity in the bovine mammary gland. In trial 1, cows were immunized by intramammary infusion of keyhole limpet hemocyanin with either saline (n = 3) or interleukin-2 (n = 3) as adjuvants. In trial 2, cows were immunized by intramuscular injection near the supramammary lymph node with keyhole limpet hemocyanin in conjunction with saline (n = 4). Freund's incomplete adjuvant (n = 4), or interleukin-2 (n = 4). Local immunization with interleukin-2 as an adjuvant significantly increased antibody titers in milk over preimmunization levels and levels in saline-treated cows. The use of Freund's incomplete adjuvant and interleukin-2 as adjuvants in cows that were immunized systemically enhanced both sera and lacteal antibodies to keyhole limpet hemocyanin. However, cows that were administered interleukin-2 responded more quickly than those given Freund's incomplete adjuvant. Only those cows that received interleukin-2 as an adjuvant demonstrated significant increases in blood lymphocyte proliferation to keyhole limpet hemocyanin, pokeweed mitogen, and interleukin-2. The results of these two trials suggest that immunization with interleukin-2 as an adjuvant may be more effective than Freund's incomplete adjuvant in enhancing specific immunity in the bovine mammary gland and may possibly be an effective adjuvant in mastitis immunization protocols.

Adjuvants, Immunologic↗

PubMed1995

Prevalence of coagulase gene polymorphism in Staphylococcus aureus isolates causing bovine mastitis.

This study was conducted to investigate polymorphism of the coagulase gene of Staphylococcus aureus causing bovine mastitis. One hundred eighty-seven strains of S. aureus were isolated from bovine mastitic milk samples obtained from 187 different Danish dairy farms. The isolates were characterised for restriction fragment length polymorphism (RFLP) of the coagulase gene. A variable region of the coagulase gene was amplified using the polymerase chain reaction (PCR) followed by AluI restriction enzyme digestion. A total of 15 different RFLP patterns were observed. The predominant pattern was found in 35% of the isolates. The ease of analysing coagulase gene polymorphisms among a large number of strains, and the multiple distinct polymorphic patterns generated, supports the use of this technique in epidemiological investigations of bovine mastitis. The predominating variants may have predelection for causing intramammary infections.

Animals↗

PubMed1994

Regulation of mammary gland macrophage tumour necrosis factor-alpha production with interferon-gamma.

Recombinant bovine interferon (rBoIFN)-gamma was found to modify the production of tumour necrosis factor (TNF-alpha) production by lipopolysaccharide (LPS) stimulated mammary gland macrophages. Alveolar macrophages isolated from bovine mammary glands were incubated with 0, 1, 10, 100 or 1000 U of rBoIFN-gamma either three hours before or three hours following stimulation with LPS. The level of TNF-alpha production was not affected when macrophages were treated with rBoIFN before LPS stimulation. In contrast, macrophages treated with 10, 100 or 1000 U of rBoIFN after stimulation with LPS produced significantly lower concentrations of TNF-alpha when compared with non-treated cultures and those treated with only 1 U of interferon (IFN)-gamma. These results indicate that IFN-gamma is capable of down-regulating the production of TNF-alpha by a local macrophage population. The ability of IFN-gamma to modify the production of TNF-alpha is dependent on the timing of administration relative to LPS exposure. The significance of these findings is that under some circumstances, low dose administration of IFN-gamma may be directly responsible for down-regulation of acute phase inflammatory responses which may prevent pathological alterations to host tissues during endotoxaemia.

Animals↗

PubMed1994

Ability of Staphylococcus aureus coagulase genotypes to resist neutrophil bactericidal activity and phagocytosis.

This study investigated the functional capabilities of neutrophils against different Staphylococcus aureus genotypes isolated from cows with mastitis. Six strains of S. aureus were chosen for use in the study, two with a common genotype, two with an intermediate genotype, and two with a rare genotype. The interaction between bacteria and neutrophils was measured by phagocytosis and bactericidal effect. The average percent killing of bacteria was lowest (40.0%) with strains belonging to the most common genotype, medium (50%) with strains belonging to the intermediate type, and highest (64.2%) with strains belonging to the rare type (P < or = 0.001). Statistically significant differences (P < or = 0.001) in the numbers of phagocytized bacteria were also found between the most prevalent type (6.27 bacteria per cell) and the other two types (intermediate type, 9.26/cell; rare type, 10.5/cell). These findings suggest that one of the reasons for the variation in prevalence of different genotypes of S. aureus in the mammary gland is due to the superior ability of some types to resist phagocytosis and/or killing by bovine neutrophils.

Animals↗

PubMed1994

Altered interleukin-2 production by lymphocyte populations from bovine leukemia virus-infected cattle.

The effects of bovine leukosis virus (BLV) on the phenotypic and functional characteristics of peripheral blood mononuclear cells were investigated. Whole blood differentials showed that persistently lymphocytotic (BLV+PL) dairy cattle had more lymphocytes and fewer neutrophils than the aleukemic seropositive (BLV+AL) or seronegative (BLV-) animals. Flow cytometric analyses of peripheral blood mononuclear cells indicated that the BLV+PL animals had more B lymphocytes, with a concomitant decrease in CD2 positive cells when compared with the BLV- group. Mononuclear cells from the BLV+AL animals also had fewer CD2 positive cells, but no differences in B lymphocytes were observed when compared with BLV- cattle. Peripheral blood mononuclear cells were used in blastogenesis assays to assess the functional ability of lymphocytes. Lymphocytes from BLV+PL animals had lower proliferative responses to concanavalin A and pokeweed mitogen when compared with cells from the BLV- or BLV+AL groups. The level of spontaneous blastogenesis in the absence of mitogenic stimulation was high for lymphocytes obtained from BLV+AL cattle. Cultures of lymphocytes obtained from BLV+PL animals produced greater amounts of interleukin-2 (IL-2) than BLV+AL and BLV- groups, although no differences were observed in the expression of IL-2 receptors. The development of uncontrolled lymphocytosis in BLV-infected cattle may result from an altered responsiveness to IL-2-regulated B-lymphocyte proliferation.

Animals↗

PubMed1993

Effects of selenium status on bovine mononuclear cell function.

The effects of selenium (Se) status on the distribution and functional capabilities of bovine peripheral blood mononuclear cells (PBMC) were examined. No differences in proliferative responses to mitogens, interleukin (IL)-2 production, IL-2 receptor expression, or lymphocyte trafficking patterns were observed between PBMC from dairy cows maintained on Se adequate or Se deficient diets. In contrast, Se deficiency significantly reduced the numbers of circulating monocytes when compared to cows fed a Se adequate diet. Differences in the number of circulating monocytes had no apparent effect on the accessary functions of these cells with respect to antigen presentation and IL-2 production. These results suggest that the effect of Se-modified diets on bovine defense mechanisms is not mediated by the ability of peripheral blood lymphocytes to respond to antigen and mature into immunocompetent cells.

Animals↗

PubMed1993

Growth responses of coliform bacteria to recombinant bovine cytokines.

Growth responses of 10 coliform isolates to recombinant bovine cytokines were measured in vitro. Six Escherichia coli and four Klebsiella pneumoniae isolates obtained from bovine IMI were tested for growth responses to recombinant bovine interleukin-1 beta, interleukin-2, and interferon-gamma. Cytokines were tested at 10(4), 10(3), 10(2), and 10 U/ml of media. Media used were a synthetic tissue culture medium, a chemically defined synthetic bacterial growth medium, and UHT sterilized milk. Bacterial counts in the synthetic tissue culture medium and UHT milk increased slightly as concentration of interferon-gamma in the media increased. Recombinant bovine interferon-gamma increased bacterial populations during the log growth phase but did not affect the number of bacteria in stationary growth phase. Bacterial growth responses were not related to either interleukin-2 or interleukin-1 beta concentrations in any of the three media. Bacterial growth responses to cytokines were not related to differences in either serum susceptibility, growth of isolates in dry cow secretion, duration of IMI from which isolates were obtained, or bacterial species.

Animals↗