Detection of PR-39, a porcine host defence peptide, in different cell sub-linages in pigs infected with Actinobacillus pleuropneumoniae

Innate immunity is critically important for the outcome of infection in many diseases. It was previously shown that cathelicidin PR-39, an important porcine multifunctional host defence peptide, is elevated in bronchoalveolar lavage fluid and respiratory tract tissue after experimental infection with Actinobacillus pleuropneumoniae (A.pp.). To date, neutrophil polymorphonuclear leukocytes (PMNs) are thought to be the only source of PR-39. The aim of this study was to further characterize PR-39⁺ cells and selected immune cell populations in lung tissue during the peracute (7-10 hours), acute (2 days), reconvalescent (7 days) and chronic (21 days) stages of experimental infection with A.pp. serotype 2. In total, six mock-infected control pigs and 12 infected pigs were examined. Using immunofluorescence double-labeling, antibodies against PR-39 were combined with antibodies against CD3 (T-cells), CD79 (B-cells), Iba1 (activated macrophages), TTF-1 (lung epithelial cells expressing surfactant proteins), macrophage/L1 protein and myeloperoxidase (MPO, cells of the myeloid linage). In the peracute and acute phases of infection, total PR-39⁺ cells and myeloid linage cells increased, whereas CD3⁺ cells and TTF-1⁺ cells decreased. Double labeling revealed that most Macrophage/L1 protein+ cells and to a lesser extent MPO⁺ cells co-expressed PR-39. In addition, few bronchial epithelial cells and type 2 alveolar epithelial cells (both identified with TTF-1) produced PR-39. Occasionally, CD3⁺ T cells expressing PR-39 were seen in infected animals. Taken together, this study identifies cell types, other than PMNs, in lungs of A.pp.-infected pigs that are capable of producing PR-39. In addition, these findings provide further insights into the dynamics of different immune cell populations during A.pp.-infection.

Respiratory disease markers in porcine bronchoalveolar lavage fluid

In bronchoalveolar lavage fluid (BALF) of pigs originating from different herds bacteria, cells and the antibacterial peptide PR‐39 were examined to gain information about the lung health status. In a high health nucleus herd 56% and in low health herds 20–100% of the examined pigs were found positive for potentially pathogenic bacteria. Based on these findings, a novel definition for bacterial respiratory tract disease was established using an 8% cut‐off for the relative number of neutrophils in bronchoscopic and a 40% cut‐off in transtracheal BALF in combination with the occurrence of potentially pathogenic microorganisms. The antibacterial peptide PR‐39 was highly correlated to this definition of respiratory disease. An assessment of the bacteriological respiratory health status appears to be possibly based on the determination of PR‐39 concentrations in BALF using different cut‐off values according to the lavage method (2.5 nM for bronchoscopic and 5 nM for transtracheal BALF).

Comparison of three common methods of lung lavage in healthy pigs

Bronchoscopic, endotracheal and transtracheal lung lavage were evaluated in 38 healthy pigs taken from a nucleus herd in a good state of health with respect to their applicability in practice and the traceability of bacteria, cellular parameters and the antimicrobial peptide PR-39 in the respective lavage fluid samples. The total cell count, qualitative morphological cellular characteristics as well as PR-39 could be determined in all lavage fluid samples, while quantitative cell differentiation was not possible in endotracheal lavage samples. The comparison of the three methods resulted in a higher proportion of polymorphonuclear neutrophil granulocytes (PMNs) and higher concentrations of PR-39 in transtracheal samples. For this reason different valuation standards with respect to PMNs and PR-39 concentrations are presupposed for transtracheal lavage samples. The occurrence of pavement epithelial cells as well as the number of contaminating bacterial species per sample was the lowest in transtracheal lavage. Mycoplasma hyopneumoniae polymerase chain reaction appeared to have the highest diagnostic sensitivity in combination with bronchoscopic lavage. In conclusion, bronchoscopic and transtracheal lavage were considered to be more appropriate for bacteriological and cytological diagnostics than endotracheal lavage.

Altered frequency responses of sympathetic nerve discharge bursts after IL-1beta and mild hypothermia

Although interleukin-1beta (IL-1beta) administration produces nonuniform changes in the level of sympathetic nerve discharge (SND), the effect of IL-1beta on the frequency-domain relationships between discharges in different sympathetic nerves is not known. Autospectral and coherence analyses were used to determine the effect of IL-1beta and mild hypothermia (60 min after IL-1beta, colonic temperature from 38 degrees C to 36 degrees C) on the relationships between renal-interscapular brown adipose tissue (IBAT) and splenic-lumbar sympathetic nerve discharges in chloralose-anesthetized rats. The following observations were made. 1) IL-1beta did not alter renal-IBAT coherence values in the 0- to 2-Hz frequency band or at the cardiac frequency (CF). 2) Peak coherence values relating splenic-lumbar discharges at the CF were significantly increased after IL-1beta and during hypothermia. 3) Hypothermia after IL-1beta significantly reduced the coupling (0-2 Hz and CF) between renal-IBAT but not splenic-lumbar SND bursts. 4) Combining IL-1beta and mild hypothermia had a greater effect on renal-IBAT SND coherence values than did mild hypothermia alone. These data demonstrate functional plasticity in sympathetic neural circuits and suggest complex relationships between immune products and SND regulation.

Interleukin-1 beta alters brown adipose tissue but not renal sympathetic nerve responses to hypothermia

Proinflammatory cytokines and acute physical stress influence sympathetic nerve discharge (SND). Because interleukin-1 beta (IL-1 beta) produces physiological responses that require central neural integration and because the sympathetic nervous system mediates physiological responses to environmental stress, we hypothesized that IL-1 beta modulates SND responses to acute physical stress. Therefore, this study examined the effects of IL-1 beta (290 ng/kg iv) and mild hypothermia on renal and interscapular brown adipose tissue (IBAT) SND regulation in chloralose-anesthetized rats. IBAT SND did not change after IL-1 beta administration but was significantly increased during acute mild hypothermia, which was induced 60 min after IL-1 beta treatment. Renal SND was unchanged after IL-1 beta administration and during hypothermia. Acute hypothermia, without prior IL-1 beta administration, did not alter IBAT and renal SND. Increases in IBAT SND during sustained (120 min) hypothermia were significantly higher in IL-1 beta-treated rats compared with saline-treated rats, whereas renal SND responses to sustained hypothermia did not differ among groups. Exposure to acute cold stress after sustained hypothermia produced greater increases in IBAT SND in IL-1 beta-treated rats compared with saline-treated controls. These data suggest that IL-1 beta alters IBAT SND responses to acute and sustained hypothermia.

Immunomodulators for prevention and treatment of infectious diseases in food-producing animals

The goal of immunomodulation in food-producing animals is to regulate immunity for the benefit of the animal and production efficiency. Immunomodulators are substances that exert this control and include cytokines, pharmaceuticals, microbial products, nutraceuticals, and traditional medicinal plants. Although treatment and prevention of infectious diseases are the most common reasons to use immunomodulators, other conditions, such as amelioration of stress-induced immunosuppression, maturation of the neonate's developing immune response, and strategies to reduce the metabolic cost of eliciting an immune response also are well suited for immunomodulation. Continued discovery of new immune regulators and increased understanding of immunity in food-producing animals will ensure new opportunities for the use of immunomodulators in food-producing animals.

Effect of cervical vagotomy on sympathetic nerve responses to peripheral interleukin-1beta

Although the vagus nerve is an important neural pathway mediating immune-to-brain communication, the role of the vagus in mediating sympathetic nerve discharge (SND) responses to peripheral cytokines is not well established. In the present study we determined renal, interscapular brown adipose tissue (IBAT), splenic, and lumbar SND responses before and for 60 min after the intravenous administration of interleukin-1beta (IL-1beta, 100 ng) in chloralose-anesthetized, sham-vagotomized and cervical-vagotomized (bilateral) rats. In sham-vagotomized rats, IL-1beta administration increased (P<0.05) splenic and lumbar SND while renal and IBAT SND remained unchanged from control levels. Renal, splenic, and lumbar SND were increased (P<0.05) whereas IBAT SND remained unchanged from control after IL-1beta in vagotomized rats. Renal, splenic, and lumbar SND responses were significantly higher after IL-1beta in vagotomized compared with sham-vagotomized rats. These results demonstrate that regionally-selective SND (renal, splenic, and lumbar) responses to IL-1beta can occur in the absence of the vagus nerve and suggest that the vagus nerve provides a tonic inhibition to the discharges in these nerves in response to peripheral IL-1beta.

Regulation of cathelicidin gene expression: induction by lipopolysaccharide, interleukin-6, retinoic acid, and Salmonella enterica serovar typhimurium infection

Cathelicidins are a family of antimicrobial peptides prominent in the host defense mechanisms of several mammalian species. In addition to their antimicrobial activities, these peptides have been implicated in wound healing, angiogenesis, and other innate immune mechanisms. To investigate the regulatory mechanisms of cathelicidin gene expression, we conducted in vitro experiments evaluating the bone marrow cell expression of two porcine cathelicidins, PR-39 and protegrin, and cloned and evaluated the promoter sequence of PR-39. In addition, we evaluated in vivo kinetics of cathelicidin gene expression in pigs during an infection with Salmonella enterica serovar Typhimurium. Lipopolysaccharide (LPS) increased PR-39 and protegrin mRNA expression, which was ameliorated by polymyxin B. Concentrations of PR-39 in supernatants from bone marrow cell cultures were increased 10-fold after LPS stimulation. Similarly, interleukin-6 (IL-6) and all-trans retinoic acid (RA) markedly induced cathelicidin gene expression. To verify the transcriptional activation of the PR-39 gene by these agents, we made a PR-39 promoter-luciferase construct containing the full-length PR-39 promoter driving luciferase gene expression and transiently transfected PK-15 epithelial cells. RA and IL-6 increased luciferase activity in PK-15 cells transfected with the PR-39 promoter-luciferase reporter. Similarly, Salmonella-challenged pigs showed increased expression of PR-39 and protegrin mRNA in bone marrow cells at 6 and 24 h postchallenge. Taken together, these findings show that bacterial products (LPS), IL-6, RA, and Salmonella infection enhance the expression of the cathelicidins, PR-39 and protegrin, in bone marrow progenitor cells, and we suggest that extrinsic modulation of this innate host defense mechanism may be possible.

Porcine antimicrobial peptides: new prospects for ancient molecules of host defense

Antimicrobial peptides (AMPs) are small, endogenous, polycationic molecules that constitute a ubiquitous and significant component of innate immunity. These natural antibiotics have broad microbicidal activity against various bacteria, fungi, and enveloped viruses. Because most AMPs kill bacteria by physical disruption of cell membranes, which may prevent microorganisms from developing resistance against these agents, they are being explored as possible alternatives to conventional antibiotics. Pigs, like many other mammals, produce an impressive array of AMPs, which are synthesized predominantly by host leukocytic phagocytes or mucosal epithelial cells. Currently, more than a dozen distinct porcine AMPs have been identified and a majority belongs to the cathelicidin family. This review briefly summarizes recent advances in porcine AMP research with an emphasis on the diverse biological functions of each peptide. Mechanisms of action of these AMPs and their role in the resistance to infections are considered. Finally, the current status of pharmaceutical and agricultural uses of AMPs as well as future prospects for their application in the food animal industry is discussed.

Cloning of porcine NRAMP1 and its induction by lipopolysaccharide, tumor necrosis factor alpha, and interleukin-1beta: role of CD14 and mitogen-activated protein kinases

The gene for natural resistance-associated macrophage protein 1 (NRAMP1) plays a dominant role in controlling the resistance of inbred mice to infection with intracellular bacteria, such as Mycobacteria, Salmonella, and Leishmania. NRAMP1 is a membrane protein with a consensus transport motif present in one of the intracellular loops. Although its functions remain unclear, recent clues suggest that NRAMP1 protein plays a potential role in ion transport, which presumably accounts for the ability of this single protein to regulate the intraphagosomal replication of several species of antigenically unrelated intracellular pathogens. Expression of NRAMP1 in mice can be induced by lipopolysaccharide (LPS) or bacterial infection; however, little is known about the mechanisms of induction. Here, we report the cloning of the full-length cDNA for porcine NRAMP1, which had over 85% identity in amino acid sequence to its congeners from humans, mice, cattle, and sheep. As for its mammalian congeners, expression of porcine NRAMP1 mRNA was cell and tissue specific and was highest in macrophages. Investigation of the molecular mechanisms by which NRAMP1 is induced showed that LPS-induced expression in macrophages, neutrophils, and peripheral blood mononuclear cells was time and dose dependent and was mediated primarily through CD14. Induction of NRAMP1 required de novo protein synthesis, and mitogen-activated protein kinases (MAPK) were essential. Blockage of either p38 or p42/44 MAPK pathways suppressed the expression of NRAMP1 to basal levels. These findings suggest that bacterial infection and proinflammatory mediators induce NRAMP1 expression via activation of MAPK pathways.

PR-39, a proline/arginine-rich antimicrobial peptide, prevents postischemic microvascular dysfunction

We and others have previously demonstrated that intestinal ischemia-reperfusion (I/R) is associated with a large increase in oxidant production that contributes to microvascular barrier disruption in the small bowel. It has been suggested that the bulk of tissue damage during reperfusion can be attributed to adherent, activated neutrophils. From these observations, we hypothesized that pretreatment with PR-39, an endogenous neutrophil antibacterial peptide that is also a potent inhibitor of the neutrophil NADPH oxidase, would prevent postischemic oxidant production and the development of oxidant-dependent sequelae to I/R such as increased venular protein leakage. To test this postulate, oxidant production, venular protein leakage, leukocyte adhesion, and leukocyte emigration were monitored during reperfusion in control (no ischemia) rat mesenteric venules and in mesenteric venules subjected to I/R alone or PR-39 + I/R. Treatment with a single intravenous bolus injection of PR-39 (administered at a dose to achieve an initial blood concentration of 5 microM) abolished I/R-induced leukocyte adhesion and emigration in vivo. In vitro studies indicated that PR-39 prevents platelet-activating factor-induced neutrophil chemotaxis as well as phorbol myristate acetate (PMA)-stimulated intercellular adhesion molecule-1 expression by cultured endothelial cells. PR-39 pretreatment of rat neutrophils also blocked PMA-stimulated neutrophil adhesion to activated endothelial monolayers. In vivo, I/R was associated with a marked and progressive increase in oxidant production and venular protein leakage during reperfusion, effects that were abolished by PR-39 treatment. The results of this study indicate that PR-39 completely abolishes postischemic leukocyte adhesion and emigration. The time course for inhibition of oxidant production by PR-39 suggests that its antiadhesive properties account for this effect of the peptide. PR-39 may thus be therapeutically useful for prevention of neutrophil adhesion and activation during the postischemic inflammatory response.

Cloning and characterization of the gene for a new epithelial beta-defensin. Genomic structure, chromosomal localization, and evidence for its constitutive expression

Mammalian beta-defensins are endogenous cysteine-rich peptide antibiotics that are produced either by epithelial cells lining the respiratory, digestive, and urogenital tracts or by granulocytes and macrophages. A growing body of evidence has implicated these peptides in host defense, particularly mucosal innate immunity. We previously reported the cloning of the full-length cDNA for a porcine beta-defensin (pBD-1), which was found to be expressed throughout the airway and oral mucosa. Here, we provide the structural organization of the pBD-1 gene, showing that the entire gene spans approximately 1.9 kilobases with two short exons separated by a 1.5-kilobase intron. Fluorescence in situ hybridization mapped the pBD-1 gene to porcine chromosome 15q14-q15. 1 within a region of conserved synteny to the chromosomal locations of human and mouse alpha- and beta-defensins. We also provide several independent lines of evidence showing that the pBD-1 gene is expressed constitutively during inflammation and infection, despite its resemblance to many inducible epithelial beta-defensins in amino acid sequence, genomic structure, and sites of expression. First, stimulation of primary porcine tongue epithelial cells with lipopolysaccharide, tumor necrosis factor-alpha, and interleukin (IL)-1beta failed to up-regulate the expression of pBD-1 mRNA. Second, pBD-1 gene expression was not enhanced in either digestive or respiratory mucosa of pigs following a 2-day infection with Salmonella typhimurium or Actinobacillus pleuropneumoniae. Last, direct transfection of the pBD-1 gene promoter into NIH/3T3 cells showed no difference in reporter gene activity in response to stimulation by lipopolysaccharide and IL-1beta. The constitutive expression of pBD-1 in airway and oral mucosa, which is consistent with a lack of consensus binding sites for nuclear factor-kappaB or NF-IL-6 in its promoter region, suggests that it may play a surveillance role in maintaining the steady state of microflora on mucosal surfaces.

Porcine epithelial beta-defensin 1 is expressed in the dorsal tongue at antimicrobial concentrations

Epithelial cells and phagocytes contain antimicrobial polypeptides that participate in innate host defense. A recently cloned porcine beta-defensin, PBD-1, was detected by Northern organ blots exclusively in the tongue epithelium. We generated recombinant PBD-1 peptide by using a baculovirus-insect cell expression system and obtained two forms (PBD-142 and PBD-138), which differed by N-terminal truncation. Only PBD-142 was found in scrapings of the surface of the dorsal tongue or the buccal mucosa. Immunohistochemical staining with antibody to PBD-142 revealed that PBD-1 was highly concentrated in an approximately 0.1-mm-thick layer in the cornified tips of the filiform (but not fungiform) papillae of the dorsal tongue and in the superficial squamous cell layers of the buccal mucosa. By scraping, extraction, and semiquantitative Western blotting, the concentration of PBD-1 in the dorsal tongue surface and the buccal mucosa was estimated at 20 to 100 micrograms/ml. PBD-1 had antibacterial activity against Escherichia coli, Salmonella typhimurium, Listeria monocytogenes, and Candida albicans in 10 mM sodium phosphate buffer (pH 7.4). Added NaCl progressively inhibited the activity of PBD-1 against E. coli and C. albicans. In 10 mM sodium phosphate with 125 mM NaCl, the combinations of sublethal concentrations of PBD-1 and the porcine neutrophil peptide PG-3, PR-39, or PR-26 showed synergistic activity against E. coli or the multidrug-resistant S. typhimurium DT104. At its physiologic concentration, PBD-1 has antimicrobial effects under both low- and high-salt conditions encountered in the oral cavity and may contribute to the antimicrobial barrier properties of the dorsal tongue and oral epithelium.

Identity of heart and liver L-3-hydroxyacyl coenzyme A dehydrogenase

Rat heart and liver cDNAs for precursor of L-3-hydroxyacyl-CoA dehydrogenase have been cloned and sequenced. The results indicate that these different rat organs express identical dehydrogenases. Furthermore, pig heart mRNA for L-3-hydroxyacyl-CoA dehydrogenase precursor was amplified by reverse transcription-polymerase chain reaction, and all the cDNA clones were found to encode a precursor of liver L-3-hydroxyacyl-CoA dehydrogenase (X.-Y. He, S.-Y. Yang, Biochim. Biophys. Acta 1392 (1998) 119-126) but not the well-documented heart form of the dehydrogenase (K.G. Bitar et al., FEBS Lett. 116 (1980) 196-198). Sequencing data and other evidence establish that the pig, like the rat, has the same dehydrogenase in heart and liver. Since the size and structure of pig heart L-3-hydroxyacyl-CoA dehydrogenase are identical to the pig liver dehydrogenase, reports that relied on the published sequence of the pig heart dehydrogenase need to be re-evaluated. For example, the signature pattern of the L-3-hydroxyacyl-CoA dehydrogenase family is HXFXPX3MXLXE. Furthermore, the published crystal structure of the pig heart dehydrogenase that substantiated each subunit comprising 307 residues with a mercury-binding residue at position 204 (J.J. Birktoft et al., Proc. Natl. Acad. Sci. U.S.A. 84 (1987) 8262-8266) must be re-examined in accordance with this revelation.

Cathelicidin gene expression in porcine tissues: roles in ontogeny and tissue specificity

Cathelicidins constitute a family of mammalian antimicrobial peptides that are synthesized in the bone marrow as prepropeptides, stored in neutrophil granules as propeptides, and released as active, mature peptides upon neutrophil degranulation. We investigated the developmental expression of two porcine cathelicidins, PR-39 and protegrin. Both cathelicidins were expressed constitutively in the bone marrow of all pigs at all of the ages tested. Peripheral blood neutrophils from young pigs expressed PR-39 and protegrin mRNA, which were not detectable at 42 days of age. At earlier ages, expression of PR-39 mRNA was detected in the kidney and liver and several lymphoid organs, including the thymus, spleen, and mesenteric lymph nodes, but disappeared at 4 weeks of age. These data provide the first evidence of cathelicidin gene expression in peripheral leukocytes and may indicate a role for these antimicrobial peptides in the development of host defense mechanisms.

Endothelial NADPH oxidase as the source of oxidants in lungs exposed to ischemia or high K+

We have previously demonstrated the generation of reactive oxygen species (ROS) in cultured bovine pulmonary artery endothelial cells (BPAECs) and in isolated perfused rat lungs exposed to high K+ and during global lung ischemia. The present study evaluates the NADPH oxidase pathway as a source of ROS in these models. ROS production, detected by oxidation of the fluorophore, dichlorodihydrofluorescein, increased 2.5-fold in BPAECs and 6-fold in rat or mouse lungs exposed to high (24 mmol/L) K+. ROS generation was markedly inhibited by diphenyliodonium, a flavoprotein inhibitor, and by the synthetic peptide PR-39, an inhibitor of NADPH oxidase assembly, whereas allopurinol had no effect. With ischemia (1 hour), ROS generation by rat and mouse lungs increased 7-fold; PR-39 showed concentration-dependent inhibition of ROS production, with 50% inhibition at 3 micromol/L PR-39. ROS production in lungs exposed to high K+ or ischemia was essentially abolished in mice with a "knockout" of gp91(phox), a membrane-localized cytochrome component of NADPH oxidase; increased ROS production by these lungs after anoxia/reoxygenation was similar to control. PR-39 also inhibited ischemia and the high K+-mediated increase in lung thiobarbituric acid reactive substance. Western blotting of BPAECs and immunocytochemistry of BPAECs and rat and mouse lungs showed the presence of p47phox, a cytoplasmic component of NADPH oxidase and the putative target for PR-39 inhibition. In situ fluorescence imaging in the intact lung demonstrated that the increased dichlorofluorescein fluorescence in these models of ROS generation was localized primarily to the pulmonary endothelium. These studies demonstrate that ROS production in lungs exposed to ischemia or high K+ results from assembly and activation of a membrane-associated NAPDH oxidase of the pulmonary endothelium.

Molecular cloning and tissue expression of porcine beta-defensin-1

Beta-defensins constitute an emerging family of cysteine-rich antimicrobial peptides, which are particularly prominent at mucosal epithelial sites in mammals. Here we report the identification of a novel beta-defensin from porcine tissues, porcine beta-defensin-1 (pBD-1). The cDNA sequence of pBD-1 encoded a 64 amino acid prepro-peptide, which contained the beta-defensin consensus sequence of six invariantly spaced cysteine residues. Northern blot analysis showed that pBD-1 was expressed abundantly in tongue epithelia and that the expression was regulated developmentally. Using RT-PCR, pBD-1 mRNA was detected throughout the respiratory and digestive tracts and also in thymus, spleen, lymph node, brain, liver, kidney, urinary bladder, testis, skin, heart, muscle, bone marrow, peripheral blood neutrophils, alveolar macrophages, and umbilical cord. The wide expression of pBD-1 suggests that this endogenous peptide antibiotic may contribute to both mucosal and systemic host defenses in pigs, which may have implications for the use of porcine tissues and organs in xenotransplantation.

Porcine myelomonocytic markers: summary of the Second International Swine CD Workshop

Forty five mAbs submitted to the Second International Swine CD workshop were analyzed by six different laboratories for their possible reactivity with porcine myelomonocytic cells using flow cytometry and immunohistochemistry. As a result of these analyses, a new swine workshop cluster, SWC9, composed of two mAbs that recognize an antigen selectively expressed on mature macrophages, was defined. In addition, several mAbs were identified, allowing the differentiation of granulocytes from monocytes/macrophages, or monocytes from macrophages. Further work is required to identify the antigen recognized by these mAbs. Nevertheless, they should already prove useful for the identification of different stages in the macrophage maturation/differentiation, and will certainly aid analyses on the complexity of the mononuclear phagocyte system in the pig. Finally, the cross-reactivity of three anti-human CD14 mAbs with porcine myelomonocytic cells was established in this workshop.

Overview of the Second International Workshop to define swine cluster of differentiation (CD) antigens

The aim of the Second International Swine Cluster of Differentiation (CD) Workshop, supported by the Veterinary Immunology Committee (VIC) of the International Union of Immunological Societies (IUIS), was to standardize the assignment of monoclonal antibodies (mAb) reactive with porcine leukocyte differentiation antigens and to define new antibody clusters. At the summary meeting of the workshop in July, 1995, revisions in the existing nomenclature for Swine CD were approved, so that the rules are now in accord with those for human and ruminant CD. Swine CD numbers will now be given to clusters of mAb to swine orthologues of human CD molecules when homology is proven by (1) suitable tissue distribution and lymphoid cell subset expression, (2) appropriate molecular mass of the antigen recognized by the mAbs, and (3) reactivity of mAbs with the cloned swine gene products, or cross-reactivity of the mAb on the human gene products. In some cases, this reactivity would not be fully proven, mainly due to the lack of cloned gene products; for these CD antigens, the respective clusters will be assigned by the prefix 'w' which will lead to 'wCD' antigens. As a result of the Second International Swine CD Workshop the assignment of 16 mAb to existing CD groups (CD2a, CD4a, CD5a, wCD6, wCD8, CD14, CD18a, wCD21, wCD25) was confirmed, and 2 mAb to existing swine workshop clusters (SWC). More importantly, for the work on the porcine immune system, was the definition of 5 new swine CD antigens, namely CD3 (recognized by 6 new mAb and 3 epitopes), CD16 (1 new mAb), wCD29 (2 mAb), CD45RA (3 mAb) and CD45RC (1 new mAb). Finally, the demarcation of two new SWC molecules in swine, SWC8 (2 mAb) and SWC9 (2 mAb) was confirmed.

Workshop studies with monoclonal antibodies identifying a novel porcine differentiation antigen, SWC9

Two monoclonal antibodies (mAb) within cluster M4 of the myeloid section of the Second International Swine CD Workshop, C4 (No. 144) and PM18-7 (No. 192), showed reactivity with thymocytes and among cells of myelomonocytic origin with mature macrophages but not with monocytes and granulocytes. Both mAb recognize a protein showing two bands of 205 kDa and 130 kDa under both reducing and non-reducing conditions. Although epitope mapping with these mAb could not be performed, this cluster received the SWC9 designation.

Salmonella infection increases porcine antibacterial peptide concentrations in serum

PR-39 is a multifunctional neutrophil peptide involved in host defense and inflammation. To investigate the involvement of PR-39 in a Salmonella choleraesuis infection, a PR-39 enzyme immunoassay was developed. The concentrations of PR-39 in serum were 13.6 +/- 1.9 ng/ml before challenge and increased (P < 0.01) threefold by 10 to 14 days postinfection. Peripheral blood neutrophil counts paralleled the changes in the concentrations of PR-39 in serum, both returned to basal values by 4 weeks postinfection. These findings suggest that the concentrations of serum PR-39 reflect the involvement of this antibacterial peptide in the host's response to an S. choleraesuis infection.

Chemoattractant properties of PR-39, a neutrophil antibacterial peptide

The proline-arginine (PR) -rich antibacterial peptide, PR-39, kills bacteria by a non-pore-forming mechanism. Because this neutrophil peptide possesses several distinct functional properties and because other antimicrobial peptides are chemoattractants, we sought to determine whether PR-39 was a chemoattractant for porcine leukocytes. The peptide was synthesized by the solid-phase method using t-Boc chemistry and purified by reversed-phase high-performance liquid chromatography. Leukocyte migration was assessed with the use of a 48-well microchemotaxis chamber. PR-39 induced the directed migration of neutrophils. The peak chemotaxis response occurred at 0.5-2 microM, which was slightly lower than the minimal inhibitory and bactericidal concentrations for PR-39. However, the peptide was not a chemoattractant for mononuclear cells. Truncation of PR-39 suggested that the neutrophil chemoattractant domain may be contained within the first 26 amino acid residues. Intracellular Ca2+ fluxes in response to PR-39 were monitored by flow cytometry and showed a transient increase that peaked at approximately 40 s and approached basal values by 4 min. However, in a Ca2+-free environment, the PR-39-induced Ca2+ increase was abrogated. Furthermore, PR-39 did not induce neutrophil chemotaxis in the absence of extracellular Ca2+, and pertussis toxin inhibited both neutrophil chemotaxis and Ca2+ mobilization. Taken together, these data suggest that PR-39 is a Ca2+-dependent chemoattractant of neutrophils. The finding of a neutrophil antibacterial peptide that is also a neutrophil chemoattractant is intriguing and may indicate an important role for PR-39 in inflammation.

Supplemental dietary chromium does not influence ACTH, cortisol, or immune responses in young calves inoculated with bovine herpesvirus-1

Twelve Holstein bull calves (6 to 8 wk of age) were used to determine the influence of supplemental dietary Cr on ACTH, cortisol, and immune responses of calves experimentally inoculated with bovine herpesvirus-1 (BHV-1). Calves supplemented with Cr received 3 mg Cr/d (Chromium, n = 6) of a high-Cr-yeast product. Following 53 d of treatment, all calves were fitted with jugular catheters, and blood samples were collected every 4 h into tubes containing ETDA. Twenty-four hours later, all calves were inoculated intranasally with BHV-1 (1 x 10(7) plaque-forming units in each naris). Serial blood collection continued at 4-h intervals for 6 d. Plasma was harvested, immediately frozen in liquid nitrogen, and stored at -20 degrees C. Individual rectal temperatures and urine samples were collected at the same time each day. Rectal temperatures were elevated (P < .05) on d 2, 3, 4, and 5 but were not affected by Cr treatment. Treatment with Cr did not affect secretion of ACTH, cortisol, or plasma tumor necrosis factor-alpha, although clear circadian variation in ACTH and cortisol occurred. No differences were detected in the concentrations of trace minerals excreted daily in the urine, lymphocyte proliferative response to mitogen stimulation, and neutrophil bactericidal function. The acute phase proteins, ceruloplasmin and fibrinogen, also were not affected by treatment or viral challenge. These data suggest the Cr supplementation using high-Cr yeast (3 mg/d) did not alter stress responses of calves experimentally inoculated with BHV-1.

Effect of molybdenum-induced copper deficiency on in vivo and in vitro measures of neutrophil chemotaxis both before and following an inflammatory stressor

Twelve Angus x Hereford heifers (avg wt = 183.6 kg) were allotted by initial liver copper (Cu) concentrations into one of two treatments. Control (n = 6) heifers were fed a basal diet supplemented to provide a dietary Cu level of 10 ppm. Molybdenum (Mo)-induced Cu-deficient heifers (n = 6) were fed an identical basal diet supplemented with sodium molybdate (Cu:Mo ratio = 1:2.5), with dietary sulfur at .3% of the total diet. Dietary treatments were delivered for 120 d, at which time Mo-supplemented heifers were considered Cu-deficient (286 and 49 ppm liver Cu for control and Mo-induced Cu-deficient, respectively). Peripheral blood neutrophils were enumerated both before and after the administration of an inflammatory stressor, a subcutaneous injection (1.5 mL) of Freund's complete adjuvant. In vitro and in vivo measures of neutrophil chemotaxis were evaluated and the expression of two adhesion molecules, CD18 and L-selectin, were analyzed by flow cytometric procedures. Molybdenum-induced Cu deficiency increased (P < .01) the number of peripheral blood neutrophils; however, in vitro neutrophil chemotaxis was not affected. In vivo neutrophil chemotaxis tended (P < .08) to be increased in Mo-induced Cu-deficient heifers (1.55 vs 2.26 x 10(6) cells/ sponge for control and Mo-supplemented, respectively). No differences in CD18 or L-selectin expression were detected between treatments. However, CD18 expression was decreased (P < .05) in both treatments following adjuvant injection. These data suggest that Mo-induced Cu deficiency results in an increase in peripheral blood neutrophil number, without altering chemotactic ability and adhesion molecule expression.

Influence of lipopolysaccharide-induced immune challenge and diet complexity on growth performance and acute-phase protein production in segregated early-weaned pigs

Segregated early-weaned pigs (initially 4.0 kg and 14 +/- 1.5 d of age) were used to quantify the effects of lipopolysaccharide (LPS)-induced immune challenge and nursery diet complexity (complex, medium, and simple) on growth performance and haptoglobin production. Three treatments of immune challenge consisted of pigs given ad libitum access to feed (control), challenged with LPS and given ad libitum access to feed (LPS-challenged), or pair-fed to receive the same amount of feed as the LPS-challenged pigs (pair-fed). The absence of interactions (P > .10) between diet complexity and immune challenge with LPS indicated that the responses were independent. Control pigs were the heaviest (P < .01), LPS-challenged the lightest (P < .01), and pair-fed intermediate in weight on d 18 after weaning. Approximately two thirds of the decreased growth of LPS-challenged pigs was due to decreased ADFI and one third was due to decreased feed efficiency (G/F). Pigs fed the complex diet were heaviest (P < .05), and pigs fed the simple diet were lightest (P < .05) on d 18 after weaning. The increased growth of pigs fed the complex compared with those fed the medium diet was due to the increased ADFI of the former. The decreased growth of pigs fed the simple diet compared with those fed the medium or complex diets was due to both decreased ADFI and G/F. The LPS-challenged pigs had increased (P < .01) haptoglobin concentrations, suggesting that inflammatory cytokine production was higher in immune-challenged pigs. These data suggest that LPS immune challenge caused decreased growth by decreasing ADFI and altering nutrient partitioning and that growth responses to diet complexity are independent of immune challenge.

PR-39, a proline-rich antibacterial peptide that inhibits phagocyte NADPH oxidase activity by binding to Src homology 3 domains of p47 phox

Reactive oxygen intermediates generated by the phagocyte NADPH oxidase are critically important components of host defense. However, these highly toxic oxidants can cause significant tissue injury during inflammation; thus, it is essential that their generation and inactivation are tightly regulated. We show here that an endogenous proline-arginine (PR)-rich antibacterial peptide, PR-39, inhibits NADPH oxidase activity by blocking assembly of this enzyme through interactions with Src homology 3 domains of a cytosolic component. This neutrophil-derived peptide inhibited oxygen-dependent microbicidal activity of neutrophils in whole cells and in a cell-free assay of NADPH oxidase. Both oxidase inhibitory and direct antimicrobial activities were defined within the amino-terminal 26 residues of PR-39. Oxidase inhibition was attributed to binding of PR-39 to the p47phox cytosolic oxidase component. Its effects involve both a polybasic amino-terminal segment and a proline-rich core region of PR-39 that binds to the p47phox Src homology 3 domains and, thereby, inhibits interaction with the small subunit of cytochrome b558, p22phox. These findings suggest that PR-39, which has been shown to be involved in tissue repair processes, is a multifunctional peptide that can regulate NADPH oxidase production of superoxide anion O2-. thus limiting excessive tissue damage during inflammation.

Antibacterial activity of a synthetic peptide (PR-26) derived from PR-39, a proline-arginine-rich neutrophil antimicrobial peptide

PR-39 is a proline-arginine-rich (PR) neutrophil antibacterial peptide originally identified and purified from the porcine small intestine. We report on the synthesis of a functional antibacterial domain of PR-39, the first 26 amino acid residues of the NH2 terminus. PR-26 was as potent as or more potent than PR-39 against enteric gram-negative bacteria. This truncated form of PR-39 potentiated neutrophil phagocytosis of Salmonella choleraesuis and decreased the level of S. typhimurium invasion into intestinal epithelial cells. Scanning electron microscopy confirmed that these peptides did not lyse cells by pore-forming mechanisms; however, they potentiated the antibacterial capabilities of a pore-forming peptide, magainin A. In addition, PR-26 was not toxic to epithelial cells at concentrations several times greater than its bactericidal concentration. These data suggest that PR-39 and its functional domain, PR-26, may potentiate the host's defense capabilities against gram-negative infections.

The effect of molybdenum-induced copper deficiency on acute-phase protein concentrations, superoxide dismutase activity, leukocyte numbers, and lymphocyte proliferation in beef heifers inoculated with bovine herpesvirus-1

This study was conducted to determine the effect of Cu deficiency on acute-phase protein concentrations, superoxide dismutase activity, leukocyte numbers, and lymphocyte proliferation in heifers inoculated with live bovine herpesvirus-1 (BHV-1). Hereford x Angus heifers were allotted by weight and initial liver Cu concentrations into molybdenum (Mo)-supplemented (n = 6) or control (n = 6) groups. Control heifers were fed a basal diet supplemented with Cu-sulfate to achieve a dietary concentration of 8 ppm of Cu. The Mo-supplemented heifers received the basal diet supplemented with Mo to achieve a dietary Mo:Cu ratio of 2.5:1 and with sulfur at .3% of the diet. All treatments were delivered for 129 d, when heifers were inoculated intranasally with BHV-1. To ensure adequate Cu stores before viral challenge, control heifers were given a cupric glycinate injection on d 100 of treatment. On d 129, Mo-supplemented heifers were considered Cu-deficient (liver Cu = 23.2 and 90.1 ppm for Mo-supplemented and control, respectively). Neutrophils were increased (P < .01) on d 129 in Mo-supplemented heifers. Ceruloplasmin, a copper-dependent acute-phase protein, increased (P < .01) by 48 h after challenge in control but not in Mo-supplemented heifers. Fibrinogen, an acute-phase protein not containing copper, increased by 48 h after challenge in Mo-supplemented but not in control heifers. Erythrocyte superoxide dismutase (SOD) activity was less (P < .05) in Mo-supplemented heifers on d 129. Viral challenge had no effect on SOD activity. Lymphocyte proliferative response to phytohemagglutinin stimulation was greater (P < .01) for Mo-supplemented heifers following BHV-1 challenge. No differences were detected when lymphocytes were stimulated with concanavalin-A or pokeweed mitogens. These data indicate that Cu deficiency alters the acute-phase protein response to viral infection and may affect lymphocyte responsiveness to mitogen stimulation.

Influence of dietary beta-glucan on growth performance, nonspecific immunity, and resistance to Streptococcus suis infection in weanling pigs

Three experiments, using 344 pigs, were conducted to evaluate the influence of beta-glucan on growth performance, neutrophil and macrophage function, haptoglobin production, and resistance to Streptococcus suis challenge in weanling pigs. In Exp. 1, 144 pigs were used to evaluate the influence of .1% dietary beta-glucan in a soybean meal- or milk protein-based diet on growth performance and neutrophil function. Pigs fed beta-glucan from d 7 to 14 after weaning had lower ADFI (P < .01) and, although not significant, ADG was lower for pigs fed beta-glucan than for pigs fed control diets. However, no differences were observed in growth performance or neutrophil function for pigs fed control or diets containing beta-glucan from d 7 to 35 after weaning. Experiment 2 was a 28-d growth assay in which pigs were fed a diet with or without .1% beta-glucan, containing 7.5% spray-dried plasma protein and 25% dried whey from d 0 to 14 after weaning. Pigs then were fed corn-soybean mealbased diets containing 2.5% spray-dried blood meal and 10% dried whey. No differences in growth performance were observed. Experiment 3 was a 35-d assay to evaluate growth performance, neutrophil and macrophage function, and plasma haptoglobin concentration. Pigs were challenged on d 28 postweaning with intravenous S. suis. In Exp. 3, pigs were fed diets without or with .025 or .05% beta-glucan. Dietary beta-glucan did not influence neutrophil or macrophage function. However, pigs fed diets containing .025% beta-glucan had increased (P < .05) ADG and ADFI and were heavier (P < .05) on d 28 after weaning than pigs fed the control diet. No differences in feed efficiency (G/F) were detected between treatments. Pigs fed beta-glucan had decreased (P < .10) plasma haptoglobin on d 14, 21, and 28 after weaning. However, Fisher's Exact test revealed that more (P < .04) pigs fed a diet containing .025% beta-glucan died by d 12 after challenge with S. suis. In conclusion, these data suggest the existence of a complex interaction involving growth performance and resistance to S. suis in pigs fed .025% beta-glucan.

Effect of copper depletion and repletion on lymphocyte blastogenesis and neutrophil bactericidal function in beef heifers

Thirty-two beef heifers were used to examine the effect of dietary copper depletion and repletion on neutrophil and lymphocyte functions. Heifers allotted to the control group (C+; n = 8) were fed a basal roughage/concentrate diet with Cu-sulfate supplementation (Cu > or = 8 ppm). To induce a Cu deficiency (depletion phase d 0 to 60), treated (T; n = 24) heifers received a diet supplemented with sulfur (.3% of diet) and sodium molybdate to achieve a Cu:Mo ratio of 1:1.5. Liver biopsies were collected on d 0, 27, and 60. Despite random allocation, T heifers had lower initial liver Cu concentrations (P < .01) than C+ heifers. At the start of the repletion phase (d 0, equal to d 60 of depletion), treated heifers were allotted by liver Cu concentration to three treatments (n = 8/treatment): Cu sulfate (S; Cu = 10 ppm), Cu proteinate (P; Cu = 10 ppm), or a negative control (C-) that remained on Mo and S supplementation. During the repletion phase, livers were biopsied on d 0, 14, and 45. By d 45, both S and P heifers had greater (P < .05) liver Cu concentrations than C- heifers. For both depletion and repletion phases, no treatment differences were detected in liver Mo or S concentrations. Jugular blood was collected on d 0, 27, and 55 of the depletion phase and d 0, 13, and 42 of the repletion phase. Neutrophils were isolated and incubated with Staphylococcus aureus to determine neutrophil bactericidal capacity (NBC).(ABSTRACT TRUNCATED AT 250 WORDS)

CD14 and other recognition molecules for lipopolysaccharide: a review

Lipopolysaccharide (LPS) or endotoxin elicits a broad, non-specific cascade of events in vivo, resulting in secretion of a variety of potent mediators and cytokines produced primarily by activated macrophages and monocytes. The overproduction of these effector molecules, such as interleukin-1 and tumor necrosis factor-alpha, contributes to the pathophysiology of endotoxic shock. Cellular recognition of LPS involves several different molecules, including cluster of differentiation antigen CD14. A thorough understanding of the interaction of LPS with cells of the immune system is necessary before effective preventative or therapeutic measures can be designed to limit the host response to endotoxin. This review discusses the role of CD14 and other LPS-recognition molecules in LPS-mediated macrophage activation.

Lipopolysaccharide modulation of a CD14-like molecule on porcine alveolar macrophages

Cluster of differentiation antigen 14 (CD14) functions as a receptor for lipopolysaccharide (LPS) LPS-binding protein (LBP) complexes. Because LPS has varying effects on CD14 expression in vitro, we evaluated CD14 expression in response to LPS with a fully differentiated macrophage phenotype, the alveolar macrophage. By using flow microfluorometric analysis and a radioimmunoassay with an anti-human CD14 monoclonal antibody (My4) that cross-reacts with porcine CD14, we found that macrophages stimulated with LPS for 24 h exhibited a two- to fivefold increase in CD14-like antigen compared with unstimulated cells. At low concentrations of LPS, up-regulation of the CD14-like antigen was dependent on serum; at higher concentrations of LPS, serum was not required. In the absence of serum a 10-fold higher dose of LPS (10 ng/ml) was required to increase CD14-like expression. In addition, LPS-induced CD14-like up-regulation correlated with secretion of tumor necrosis factor-alpha, regardless of serum concentration. Blockade with My4 antibody significantly inhibited LPS-induced tumor necrosis factor-alpha secretion at 1 ng/ml of LPS. However, inhibition decreased as we increased the LPS concentration, suggesting the existence of CD14-independent pathways of macrophage activation in response to LPS. Alternatively, My4 may have a lower affinity for the porcine CD14 antigen than LPS, which may have only partially blocked the LPS-LBP binding site at high concentrations of LPS. Therefore, these data suggest that LPS activation of porcine alveolar macrophages for 24 h increased CD14-like receptor expression. The degree of CD14-like up-regulation was related to LPS concentration, however, activation did not require the presence of serum at high concentrations of LPS.

Stress-associated concentrations of plasma cortisol cannot account for reduced lymphocyte function and changes in serum enzymes in lambs exposed to restraint and isolation stress

Lambs were used to evaluate the effect of stress-associated plasma concentrations of cortisol on measures of immune function. Lambs given restraint and isolation stress (RIS) were isolated from visual and tactile contact with other lambs for 6 h on three consecutive days. Additional lambs were infused with cortisol (CORT) to increase plasma concentrations similar to those in lambs subjected to RIS. Control lambs (CON) were undisturbed. On the 1st and 3rd d of the experiment, plasma was obtained hourly during treatment for quantification of cortisol and ACTH. Blood mononuclear cells were obtained 24 h before the 1st d of treatment and daily at the conclusion of treatment for responses to phytohemagglutinin (PHA), concanavalin A (Con A), and pokeweed mitogen (PWM); for production of interleukin 2 (IL2); and for identification of cells expressing major histocompatibility complex class II antigens (MHCII). Combined fitted profiles of cortisol in RIS and CORT lambs differed (P < .005) from those in CON on both days evaluated. Fitted profiles of cortisol were similar between RIS and CORT lambs on the 1st d of treatment but differed (P < .005) on the 3rd d. Combined fitted profiles of ACTH from CON and CORT lambs differed from those of RIS lambs on both days of treatment (P < .005). Lymphocyte responses to PHA (P < .01), Con A (P < .01), and PWM (P < .07) were less in RIS than in CON but did not differ between CON and CORT. Treatment did not affect IL2 or MHCII. Increased plasma cortisol measured during RIS cannot alone account for reduced lymphocyte proliferative responses.

Influence of recombinant bovine interleukin-1 beta and interleukin-2 in pigs vaccinated and challenged with Streptococcus suis

An experiment was conducted to determine the adjuvanticity of recombinant bovine IL-1 beta (rBoIL-1 beta) and recombinant bovine IL-2 (rBoIL-2) administered in conjunction with a single Streptococcus suis vaccination in pigs. Sixty 4-week-old pigs were allotted to eight groups: nonvaccinated controls; vaccinated controls; rBoIL-beta at 0.1, 1, and 10 micrograms kg-1; rBoIL-2 at 2.5, 25, and 250 micrograms kg-1. All pigs (except nonvaccinated controls) were vaccinated on Day 0 with a commercial Streptococcus suis vaccine (serotypes 1 and 2). At vaccination, pigs were injected intramuscularly with their respective cytokine treatments. Pigs received additional cytokine injections on 2 consecutive days. On Day 21, all pigs were challenged intravenously with 3.2 x 10(9) colony forming units of a log phase culture of S. suis (serotype 2). The highest dose of rBoIL-1 beta exceeded the maximum tolerable dose for the cytokine; however, this dose of rBoIL-1 beta protected pigs from the S. suis challenge. Pigs administered rBoIL-1 beta at 10 micrograms kg-1 had higher antibody responses to S. suis, less severe clinical signs of the disease after challenge, better growth performance during the infection, and less severe gross pathological lesions caused by the bacteria. No pigs in this treatment group died from the bacterial challenge. These data suggest that rBoIL-1 beta (10 micrograms kg-1), administered intramuscularly for 3 consecutive days at vaccination, is more effective than a single S. suis vaccination alone in protecting pigs against a S. suis challenge.

Identification of a proline-arginine-rich antibacterial peptide from neutrophils that is analogous to PR-39, an antibacterial peptide from the small intestine

Neutrophil nonoxidative defense mechanisms include several low molecular weight antimicrobial peptides. We have isolated a proline-arginine-rich antibacterial peptide from porcine neutrophils. This cationic, low molecular weight peptide has a very high degree of identity (97%) to a bactericidal peptide, PR-39, that has been found in the porcine small intestine. Isolation of the same antimicrobial peptide from both neutrophils and cells of the small intestine in the same species is unique and suggests an important role for this protein in innate immune defenses.

Competitive binding analysis of monoclonal antibodies reactive with porcine alveolar macrophages using anti-CD14 and anti-CD18

Four monoclonal antibodies (mAb) from the myeloid subset panel of the First International Swine CD Workshop (74-22-15, DH59B, PM16-6, and MUC21A) were analyzed using competitive inhibition studies with anti-human CD14 (My4) and anti-human/anti-porcine CD18 (MHM23) on porcine alveolar macrophages. Results suggested that none of the mAb tested recognized CD14 or CD18 on porcine alveolar macrophages. Additionally, the cross-reactivity of My4 with porcine alveolar macrophages was established.

Workshop studies on monoclonal antibodies reactive against porcine myeloid cells

Investigators from eight laboratories analyzed the reactivity of 22 monoclonal antibodies (mAb) against porcine myeloid cells. Based on binding data, clustering analysis and inhibition studies, workshop mAb 74-22-15 (003) and 6F3 (007) were assigned a swine workshop cluster number 3 (SWC3). These mAb recognized macrophages and neutrophils; neutrophils; a monocyte/macrophage-specific mAb was not identified by this workshop.

Influence of interleukin-1 on neutrophil function and resistance to Streptococcus suis in neonatal pigs

Nonspecific immunity is usually lower in neonates than adults. Consequently, enhancing the neonate's nonspecific immune capability may be beneficial for the health and growth performance of young animals. We conducted two experiments in which neonatal pigs were injected with recombinant bovine interleukin-1 beta (rBoIL-1 beta) at 9 to 11 days of age. Three consecutive daily injections of rBoIL-1 beta increased neutrophil and monocyte numbers, which remained elevated until the animals were challenged with Streptococcus suis at 19 days of age. Neutrophil bactericidal activity was greater in interleukin-1-treated pigs than in saline-injected controls. At lower ratios of effector to target cells, neutrophil-mediated, antibody-dependent cellular cytotoxicity was increased in neonates treated with IL-1. However, natural killer cell activity and neutrophil production of superoxide anion were not affected by treatment with IL-1. Expression of CD18 was increased transiently on neutrophils from IL-1-treated pigs at 15 days of age. Severity of the streptococcal infection was less in pigs that were treated with IL-1 at 9 to 11 days of age. These data suggest that IL-1 treatment in neonates may augment nonspecific immune function and disease resistance.

Leukocyte functions of young dairy calves fed milk replacers supplemented with vitamins A and E

Holstein calves (n = 44) were fed milk replacers from d 3 to 45 with low or high concentrations of vitamin A (7000 or 87,000 IU/kg) and vitamin E (11.2 or 57 IU/kg) to examine the influence of vitamin concentrations on vitamin bioavailability and leukocyte functions. Concentrations of alpha-tocopherol in plasma reflected increased vitamin E but were unaffected by increased vitamin A. Plasma retinol concentrations were greatest with high supplementation of vitamins A and E at wk 3; however, at wk 6, plasma of calves fed high vitamin A and low vitamin E contained the most retinol. Increased supplementation of vitamin A improved fecal consistency compared with that for calves fed the low vitamin A diet at wk 3 and 4. At wk 3, calves that received increased supplementation of vitamins E and A had enhanced neutrophil bactericidal activity compared with that of calves with increased individual vitamins. Lymphocyte DNA synthesis and chemotactic index were unaffected by dietary treatments. Results indicate that increased vitamin A in milk replacer did not affect plasma vitamin E concentrations, benefited fecal scores regardless of vitamin E concentrations, but was only beneficial to bactericidal activity of neutrophils in conjunction with increased vitamin E.

Vitamin concentration and function of leukocytes from dairy calves supplemented with vitamin A, vitamin E, and beta-carotene in vitro

Blood neutrophils and pulmonary alveolar macrophages, isolated from calves at 3 and 6 wk of age, were cultured in medium without added vitamins or supplemented with 100 micrograms/dl of vitamin A, 1000 micrograms/dl of vitamin E, 100 micrograms/dl of vitamin A plus 1000 micrograms/dl of vitamin E, or .25 micrograms/dl of beta-carotene plus 1000 micrograms/dl of vitamin E. Macrophage bactericidal activity improved with supplementation of vitamins A plus E compared with supplementation of beta-carotene plus E or vitamin E at wk 3. Neutrophil bactericidal activity decreased with all vitamin E treatments at wk 3 and with vitamins E or A plus E at wk 6. Neutrophil phagocytosis improved at wk 3 with supplementations of vitamins A, E, and A plus E. The chemotactic index improved with beta-carotene and vitamin E compared with vitamin E alone at wk 3 and at wk 6 with vitamin E compared with vitamin A and control treatments. Retinol content of neutrophils varied at wk 3, but, by wk 6, cells supplemented with vitamins A, E, or A plus E had greater retinol concentrations than control cells. Neutrophil alpha-tocopherol concentrations at wk 3 increased from those of controls with supplementation of vitamin E or beta-carotene and vitamin E, but, at wk 6, vitamin E-supplemented cells were different only from vitamin A-supplemented cells. These data suggest that optimal plasma concentrations of vitamins A and E exist for leukocyte function.

Lymphocyte proliferative responses in neonatal pigs with high or low plasma cortisol concentration after stress induced by restraint

High plasma cortisol concentration is associated with perception of stress and reduced immune function in pigs. Neonatal pigs (12, 19, or 26 days old) were tested to determine maximal cortisol response to a mild restraint stressor. Pigs were fitted with indwelling jugular cannulas 4 days prior to restraint. One day before restraint, 10 ml of blood was removed for lymphocyte isolation and subsequent in vitro lymphocyte proliferation and interleukin 2 (IL-2) assays. On the day of restraint, blood samples were drawn 10 minutes before and 3, 10, and 20 minutes after holding each pig in a supine position for 1 minute. Plasma cortisol concentration was determined by use of radioimmunoassay. Pigs with maximal cortisol response greater than the mean value for that age group were classified in the high-responder (HIRES) group. Conversely, those with values lower than the mean maximal response were assigned to the low-responder (LORES) group. The HIRES pigs had larger relative adrenal gland weights and higher baseline and maximal cortisol responses, compared with LORES pigs (P = 0.0170, P = 0.0002, P = 0.0001, respectively). Mitogen-induced lymphocyte proliferative responses (to phytohemagglutinin, concanavalin A, and pokeweed mitogen) were 60% lower (P = 0.0037, P = 0.0432, P = 0.0103, respectively) in HIRES vs LORES pigs. In vitro IL-2 production did not differ between HIRES and LORES pigs.

The effect of pre- and postweaning exposure to soybean meal on growth performance and on the immune response in the early-weaned pig

The effect of pre- and postweaning exposure to soybean meal on postweaning growth performance and immune response by the early-weaned pig was analyzed. In Exp. 1, treatments were assigned in a 2 x 2 x 2 factorial arrangement. Pigs were derived from gilts fed either a soybean meal- or a corn gluten meal-based diet during gestation and lactation. Six to eight pigs per litter were either stomach-infused with or without (placebo) soybean meal during d 5 to 9 after farrowing. At weaning, 240 pigs (initially 5.1 kg, 21 +/- 1 d) were randomly allotted to either a corn-soybean meal or a corn-dried skim milk-dried whey diet based on gilt and infusion treatments. Average daily gain, ADFI, and gain:feed ratio were decreased (P < .05) on d 0 to 14 postweaning for pigs fed a soybean meal diet compared with pigs fed a milk diet. Skin-fold thickness after intradermal injection of soy protein and casein extracts on d 6 and measured on d 7 postweaning was not affected (P > .10) by dietary treatment, but serum immunoglobulin G titers to soybean glycinin and beta-conglycinin were increased (P < .01). From d 14 to 35 postweaning, all pigs were fed a common (1.25% lysine) corn-soybean meal diet containing 10% dried whey. Average daily gain, ADFI, and gain:feed ratio were decreased (P < .05) from d 14 to 35 for pigs fed a milk diet on d 0 to 14 postweaning. Serum immunoglobulin G titers were higher (P < .01) on d 21 postweaning for pigs fed soybean meal for the entire nursery period. Cumulative ADG (d 0 to 35) and gain:feed ratio were decreased (P < .05) for pigs fed a milk diet from d 0 to 14 compared with pigs fed a soybean meal diet. In Exp. 2, 104 pigs (initially 5.3 kg, 21 +/- 1 d of age) were used to determine the effect of 0, 7.5, 15.0, and 22.5% soybean meal in a high-nutrient-dense starter pig diet. Differences were not detected (P > .10) in ADG, ADFI, and gain:feed ratio during d 0 to 14, but ADFI decreased (linear, P < .05) and gain:feed ratio increased (linear, P < .05) during d 14 to 35 and for the entire 35-d trial as the level of soybean meal increased.(ABSTRACT TRUNCATED AT 400 WORDS)

Immunopotentiation of bovine respiratory disease virus vaccines by interleukin-1 beta and interleukin-2

Three experiments, using 85 crossbred beef calves, were conducted to evaluate the adjuvanticity of single, multiple, and combined doses of recombinant bovine IL-1 beta (rBoIL-1 beta) and recombinant bovine IL-2 (rBoIL-2), with a modified-live bovine herpesvirus-1/parainfluenza-3 (BHV-1/PI-3) virus vaccine and a killed bovine viral diarrhea (BVD) virus vaccine. Cytokines were administered intramuscularly at vaccination but at different injection sites. All cytokine treatments increased non-major histocompatibility complex (MHC)-restricted cytolytic capability of peripheral blood mononuclear cells (PBMC) against virus-infected target cells and serum neutralizing (SN) antibody titers to BHV-1 and BVD virus. Multiple, consecutive injections of rBoIL-2 generally showed the greatest adjuvant effect, and no additive effect was observed when rBoIL-1 beta and rBoIL-2 were administered together. In a challenge experiment, calves were vaccinated with a modified-live BHV-1/PI-3 vaccine and infected with BHV-1 on Day 21. Cytokine-treated calves had higher SN antibody titers to BHV-1 than did the control calves at the time of challenge. Calves that were administered rBoIL-2 on 5 consecutive days shed less BHV-1 and had the highest SN antibody titer to BHV-1 (Day 28). These data suggest that rBoIL-1 beta and rBoIL-2 may be useful immunoadjuvants for bovine respiratory disease virus vaccines.

Isolation and characterization of monoclonal antibodies to recombinant bovine interleukin-1 beta

We describe the preparation of monoclonal antibodies (Mabs) directed against recombinant bovine interleukin-1 beta (rBoIL-1 beta). These anti-IL-1 beta Mabs were designated SA10, SA12, SA13, SA15, and SA22, and were characterized on the basis of their epitope specificity and cross-reactivity with homologous and heterologous cytokines in enzyme-linked immunosorbent assays and immunoblot analyses. Additionally, the ability of these Mabs to neutralize IL-1 beta was tested in thymocyte costimulation assays. The ELISA titers of all Mabs ranged from 9.4 x 10(6) to 1 x 10(7). Data indicate that Mabs SA10, SA12, SA15, and SA22 neutralized both bovine macrophage-derived IL-1 (1:4) and rBoIL-1 beta (1 ng ml-1). All the Mabs against rBoIL-1 beta (SA10, SA12, SA13, SA15, SA22) were specific and did not cross-react with other cytokines tested, except recombinant human IL-1 beta (rHuIL-1 beta). This finding suggests that these Mabs recognize epitopes common to human and bovine IL-1 molecules. Competition experiments suggested that Mab SA22 recognized a different epitope and Mabs SA10, SA12, SA13, and SA15 recognized the same epitope on the rBoIL-1 beta molecule. These observations suggest that these Mabs could be useful reagents for developing immunoassays to measure bovine IL-1 beta from biological fluids and to study the immunoregulatory role of IL-1 in the bovine immune system.

Comparison of bovine immune responses to affinity-purified bovine herpesvirus-1 antiidiotypes and glycoproteins

Bovine immune responses to rabbit antiidiotypic antibodies (anti-Id) against neutralizing monoclonal antibodies to bovine herpesvirus-1 (BHV-1) envelope glycoproteins and to BHV-1 glycoproteins were compared. Glycoprotein-immunized animals produced high titers of anti-BHV-1 antibodies and were protected against BHV-1 challenge. Recombinant bovine interleukin-2 (rIL-2)-treated, anti-Id-immunized animals showed a slight reduction in clinical disease, and one calf produced BHV-1-neutralizing antibodies. Treatment with rIL-2 augmented non-BHV-1-specific immune responses. However, even with rIL-2 as an adjuvant, the mixture of polyclonal anti-Id did not elicit a consistent, protective BHV-1-specific immune response in calves.