Distinct reactivities of interleukin-4-specific antibodies with recombinant and native canine interleukin-4 in various assays

Interleukin 4 (IL-4) plays a central role in immune responses to parasites and allergens. IL-4 drives the differentiation of naive T cells into Th2 cells and regulates immunoglobulin class switching to IgE.Little is known about the role of IL-4 in canine allergies and parasite infections. Most of the information derives from measurement of IL-4 mRNA expression in dog tissues, but detection of IL-4 protein has been difficult so far, probably due to low sensitivity of available methods. Antibodies (Ab) specific for canine IL-4 are available from various sources, but these Ab have been produced against recombinant Escherichia coli-expressed canine IL-4 and there is only limited information on their reactivities with native canine IL-4. Therefore, in the present study, we tested six available canine IL-4-specific Ab for their reactivities with recombinant canine IL-4 expressed in E. coli (rec.IL-4) or in mammalian cells (mam.IL-4), and with supernatants from stimulated canine peripheral blood mononuclear cells (PBMCs) using several detection methods, including Western blotting, ELISA, cytokine bead assay, and intracellular IL-4 staining. Additionally, we tested a bovine IL-4-specific antibody that has been previously shown to cross-react with canine IL-4. All tested Ab except anti-bovine IL-4 reacted with rec.IL-4, and most of them reacted with mam.IL-4. However, only the cytokine bead assay was sensitive enough to allow the detection of IL-4 in supernatants of canine PBMCs.

Eosinophilic esophagitis in adults--no clinical relevance of wheat and rye sensitizations

BACKGROUND: Eosinophilic esophagitis (EE) is often associated with concomitant atopic diseases. In children with EE in whom food allergens have been identified as causative factors, elemental and elimination diets result in an improvement or resolution of symptoms. Most adult EE patients are sensitized to aeroallergens, which cross-react with plant-derived food allergens, most commonly to grass pollen and cereals. AIMS OF THE STUDY: To investigate the clinical relevance of the sensitization to wheat and rye, and the efficacy of an allergen-specific elimination diet in adult EE patients. METHODS: Six patients (five men, one women) with permanently active EE sensitized to grass pollen and the cereals wheat and rye underwent a double-blind placebo-controlled food challenge and were kept on an elimination diet avoiding wheat and rye for 6 weeks. RESULTS: The challenge tests with wheat and rye did not provoke any EE symptoms in all patients. The elimination diet failed in reducing disease activity. Although one patient noticed an improvement of symptoms, endoscopic and histopathologic findings remained unchanged. CONCLUSIONS: In adult EE patients, sensitization to wheat and rye does not seem causative for EE. Elimination diet is not a reliable and efficient therapeutic measure in EE patients sensitized to wheat and rye. Low specific immunoglobulin-E levels to wheat and rye may be a consequence of the underlying grass pollen allergy.

Activation of T cells by carbamazepine and carbamazepine metabolites

BACKGROUND: T-cell-mediated hypersensitivity is a rare but serious manifestation of drug therapy. OBJECTIVES: To explore the mechanisms of drug presentation to T cells and the possibility that generation of metabolite-specific T cells may provoke cross-sensitization between drugs. METHODS: A lymphocyte transformation test was performed on 13 hypersensitive patients with carbamazepine, oxcarbazepine, and carbamazepine metabolites. Serial dilution experiments were performed to generate drug (metabolite)-specific T-cell clones to explore the structural basis of the T-cell response and mechanisms of antigen presentation. 3-Dimensional energy-minimized structures were generated by using computer modeling. The role of drug metabolism was analyzed with 1-aminobenzotriazole. RESULTS: Lymphocytes and T-cell clones proliferated with carbamazepine, oxcarbazepine, and some (carbamazepine 10,11 epoxide, 10-hydroxy carbamazepine) but not all stable carbamazepine metabolites. Structure activity studies using 29 carbamazepine (metabolite)-specific T-cell clones revealed 4 patterns of drug recognition, which could be explained by generation of preferred 3-dimensional structural conformations. T cells were stimulated by carbamazepine (metabolites) bound directly to MHC in the absence of processing. The activation threshold for T-cell proliferation varied between 5 minutes and 4 hours. 1-Aminobenzotriazole, which inhibits cytochrome P450 activity, did not prevent carbamazepine-related T-cell proliferation. Substitution of the terminal amine residue of carbamazepine with a methyl group diminished T-cell proliferation. CONCLUSION: These data show that carbamazepine and certain stable carbamazepine metabolites stimulate T cells rapidly via a direct interaction with MHC and specific T-cell receptors. CLINICAL IMPLICATIONS: Some patients with a history of carbamazepine hypersensitivity possess T cells that cross-react with oxcarbazepine, providing a rationale for cross-sensitivity between the 2 drugs.

Partial overlap of anti-mycobacterial, and anti-Saccharomyces cerevisiae mannan antibodies in Crohn's disease

AIM: To test whether humoral immune reaction against mycobacteria may play a role in anti-Saccharomyces cerevisiae antibodies (ASCA) generation in Crohn's disease (CD) and/or whether it correlates with clinical subtypes. METHODS: The dominant ASCA epitope was detected by Galanthus nivalis lectin (GNL)-binding assay. ASCA and IgG against mycobacterial lysates (M avium, M smegmatis, M chelonae, M bovis BCG, M avium ssp. paratuberculosis (MAP)] or purified lipoarabinomannans (LAM) were detected by ELISA. ASCA and anti-mycobacterial antibodies were affinity purified to assess cross-reactivities. Anti-mycobacterial IgG were induced by BCG-infection of mice. RESULTS: GNL bound to different extents to mycobacterial lysates, abundantly to purified mannose-capped (Man) LAM from M tuberculosis, but not to uncapped LAM from M smegmatis. Fifteen to 45% of CD patients but only 0%-6% of controls were seropositive against different mycobacterial antigens. Anti-mycobacterial IgG correlated with ASCA (r = 0.37-0.64; P = 0.003-P < 0.001). ASCA-positivity and deficiency for mannan-binding lectin synergistically associated with anti-mycobacterial IgG. In some patients, anti-mycobacterial antibodies represent cross-reactive ASCA. Vice-versa, the predominant fraction of ASCA did not cross-react with mycobacteria. Finally, fistulizing disease associated with antibodies against M avium, M smegmatis and MAP (P = 0.024, 0.004 and 0.045, respectively). CONCLUSION: Similar to ASCA, seroreactivity against mycobacteria may define CD patients with complicated disease and a predisposition for immune responses against ubiquitous antigens. While in some patients anti-mycobacterial antibodies strongly cross-react with yeast mannan; these cross-reactive antibodies only represent a minor fraction of total ASCA. Thus, mycobacterial infection unlikely plays a role in ASCA induction.

Development of two real-time PCR assays for the detection of Mycoplasma hyopneumoniae in clinical samples

In order to improve the diagnosis of enzootic pneumonia (EP) in pigs two real-time polymerase chain reaction (rtPCR) assays for the detection of Mycoplasma hyopneumoniae in bronchial swabs from lung necropsies were established and validated in parallel. As a gold standard, the current "mosaic diagnosis" was taken, including epidemiological tracing, clinical signs, macro- and histopathological lesions of the lungs and immunofluorescence. One rtPCR is targeting a repeated DNA element of the M. hyopneumoniae genome (REP assay), the other a putative ABC transporter gene (ABC assay). Both assays were shown to be specific for M. hyopneumoniae and did not cross react with other bacteria and mollicutes from pig. With material from pigs of defined EP-negative farms the two assays showed to be 100% specific. When testing lungs from pig farms with EP, the REP assay detected 50% and the ABC assay 90% of the farms as positive. Both tests together detected all positive farms. Within a positive herd the two assays tested similarly with on average over 90% of the lung samples analysed from a single farm showing positive scores. A series of samples with suspicion of EP and samples from pigs with diseases other than respiratory taken from current routine diagnostic was assayed. None of the assays showed false positive results. The sensitivities in this sample group were 50% for the REP and 70% for the ABC assays and for both assays together 85%. The two assays run in parallel are therefore a valuable tool for the improvement of the current diagnosis of EP.

Non-pathogenic Actinobacillus isolates antigenically and biochemically similar to Actinobacillus pleuropneumoniae: a novel species?

Two unusual Actinobacillus isolates were recovered from pigs with no clinical signs, no lesions and no history of swine pleuropneumonia. Two representative strains (9953L55 and 0347) analyzed in this study were initially biochemically and antigenically identified as A. pleuropneumoniae serotypes 1 and 9, respectively, by traditional identification methods. Both strains presented, however, negative results with three A. pleuropneumoniae-specific PCR tests and revealed in particular the absence of the apxIV toxin genes. However, both strains produced and secreted ApxII toxin although they only harbored the toxin genes apxIICA, which is an uncommon feature for any of the known A. pleuropneumoniae serotypes. Upon experimental inoculation of pigs, these strains proved to be totally non-pathogenic. Animals infected with one of the strains produced antibodies that cross-react with A. pleuropneumoniae serotypes 1-9-11-specific LC-LPS ELISA. Phylogenetic analysis based on 16S rRNA gene sequence analysis revealed that these strains form a separate phylogenetic group that is distinct from other Actinobacillus species and is particularly different from A. pleuropneumoniae.

Apx toxins in Pasteurellaceae species from animals

Pasteurellaceae species particularly of porcine origin which are closely related to Actinobacillus pleuropneumoniae were analyzed for the presence of analogues to the major A. pleuropneumoniae RTX toxin genes, apxICABD, apxIICA and apxIIICABD and for their expression. Actinobacillus suis contains both apxICABD(var.suis) and apxIICA(var. suis) operons and was shown to produce ApxI and ApxII toxin. Actinobacillus rossii contained the operons apxIICA(var.rossii) and apxIIICABD(var.rossii). However, only the toxin ApxII and not ApxIII could be detected in cultures of A. rossii. The Apx toxins found in A. suis and A. rossi may play a role in virulence of these pathogens. Actinobacillus lignieresii, which was included since it is phylogenetically very closely related to A. pleuropneumoniae, was found to contain a full apxICABD(var.lign.) operon which however lacks the -35 and -10 boxes in the promoter sequences. As expected from these results, no expression of ApxI was detected in A. lignieresii grown under standard culture conditions. Actinobacillus seminis, Actinobacillus equuli, Pasteurella aerogenes, Pasteurella multocida, Haemophilus parasuis, and also Mannheimia (Pasteurella) haemolytica, which is known to secrete leukotoxin, were all shown to be devoid of any of the apx toxin genes and did not produce ApxI, ApxII or ApxIII toxin proteins. However, proteins of slightly lower molecular mass than ApxI, ApxII and ApxIII which showed limited cross-reactions with monospecific, polyclonal anti-ApxI, anti-ApxII and anti-ApxIII were detected on immunoblot analysis of A. equuli, A. seminis and P. aerogenes. The presence of Apx toxins and proteins that imunologically cross react with Apx toxins in porcine Actinobacillus species other than A. pleuropneumoniae can be expected to interfere with serodiagnosis of porcine pleuropneumonia.

Strategy for monitoring T cell responses to NY-ESO-1 in patients with any HLA class I allele

NY-ESO-1 elicits frequent antibody responses in cancer patients, accompanied by strong CD8+ T cell responses against HLA-A2-restricted epitopes. To broaden the range of cancer patients who can be assessed for immunity to NY-ESO-1, a general method was devised to detect T cell reactivity independent of prior characterization of epitopes. A recombinant adenoviral vector encoding the full cDNA sequence of NY-ESO-1 was used to transduce CD8-depleted peripheral blood lymphocytes as antigen-presenting cells. These modified antigen-presenting cells were then used to restimulate memory effector cells against NY-ESO-1 from the peripheral blood of cancer patients. Specific CD8+ T cells thus sensitized were assayed on autologous B cell targets infected with a recombinant vaccinia virus encoding NY-ESO-1. Strong polyclonal responses were observed against NY-ESO-1 in antibody-positive patients, regardless of their HLA profile. Because the vectors do not cross-react immunologically, only responses to NY-ESO-1 were detected. The approach described here allows monitoring of CD8+ T cell responses to NY-ESO-1 in the context of various HLA alleles and has led to the definition of NY-ESO-1 peptides presented by HLA-Cw3 and HLA-Cw6 molecules.

Biosynthesis of the Pseudomonas polyketide coronafacic acid requires monofunctional and multifunctional polyketide synthase proteins

Coronafacic acid (CFA) is the polyketide component of the phytotoxin coronatine, a virulence factor of the plant pathogen Pseudomonas syringae. Our current knowledge of polyketide biosynthesis largely is based on the analysis of polyketide synthases (PKSs) in actinomycetes and other Gram-positive bacteria. Consequently, the cloning and characterization of the CFA biosynthetic gene cluster will contribute significantly to our knowledge of polyketide synthesis in Pseudomonas. In this report, we describe two genes in the CFA biosynthetic gene cluster that encode PKSs that are structurally and functionally similar to the multifunctional modular PKSs, which catalyze the synthesis of macrolide antibiotics. The CFA PKS genes were overproduced in Escherichia coli and shown to cross-react with antisera made to a modular PKS involved in erythromycin synthesis. A scheme for CFA biosynthesis is presented that incorporates the activities of all proteins in the CFA PKS. In this report a gene cluster encoding a pseudomonad polyketide has been completely sequenced and the deduced gene functions have been used to develop a biosynthetic scheme.

Production, specificity, and functionality of monoclonal antibodies to specific peptide–major histocompatibility complex class II complexes formed by processing of exogenous protein

Several unanswered questions in T cell immunobiology relating to intracellular processing or in vivo antigen presentation could be approached if convenient, specific, and sensitive reagents were available for detecting the peptide–major histocompatibility complex (MHC) class I or class II ligands recognized by αβ T cell receptors. For this reason, we have developed a method using homogeneously loaded peptide–MHC class II complexes to generate and select specific mAb reactive with these structures using hen egg lysozyme (HEL) and I-Ak as a model system. mAbs specific for either HEL-(46–61)–Ak or HEL-(116–129)–Ak have been isolated. They cross-react with a small subset of I-Ak molecules loaded with self peptides but can nonetheless be used for flow cytometry, immunoprecipitation, Western blotting, and intracellular immunofluorescence to detect specific HEL peptide–MHC class II complexes formed by either peptide exposure or natural processing of native HEL. An example of the utility of these reagents is provided herein by using one of the anti-HEL-(46–61)–Ak specific mAbs to visualize intracellular compartments where I-Ak is loaded with HEL-derived peptides early after antigen administration. Other uses, especially for in vivo tracking of specific ligand-bearing antigen-presenting cells, are discussed.

Guard Cells Possess a Calcium-Dependent Protein Kinase That Phosphorylates the KAT1 Potassium Channel1

Increasing evidence suggests that changes in cytosolic Ca2+ levels and phosphorylation play important roles in the regulation of stomatal aperture and as ion transporters of guard cells. However, protein kinases responsible for Ca2+ signaling in guard cells remain to be identified. Using biochemical approaches, we have identified a Ca2+-dependent protein kinase with a calmodulin-like domain (CDPK) in guard cell protoplasts of Vicia faba. Both autophosphorylation and catalytic activity of CDPK are Ca2+ dependent. CDPK exhibits a Ca2+-induced electrophoretic mobility shift and its Ca2+-dependent catalytic activity can be inhibited by the calmodulin antagonists trifluoperazine and N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide. Antibodies to soybean CDPKα cross-react with CDPK. Micromolar Ca2+ concentrations stimulate phosphorylation of several proteins from guard cells; cyclosporin A, a specific inhibitor of the Ca2+-dependent protein phosphatase calcineurin enhances the Ca2+-dependent phosphorylation of several soluble proteins. CDPK from guard cells phosphorylates the K+ channel KAT1 protein in a Ca2+-dependent manner. These results suggest that CDPK may be an important component of Ca2+ signaling in guard cells.

Inositol 1,4,5-trisphosphate receptor subtype 3 in pancreatic islet cell secretory granules revisited.

It has been reported that the inositol 1,4,5-trisphosphate receptor subtype 3 is expressed in islet cells and is localized to both insulin and somatostatin granules [Blondel, O., Moody, M. M., Depaoli, A. M., Sharp, A. H., Ross, C. A., Swift, H. & Bell, G. I. (1994) Proc. Natl. Acad. Sci. USA 91, 7777-7781]. This subcellular localization was based on electron microscope immunocytochemistry using antibodies (affinity-purified polyclonal antiserum AB3) directed to a 15-residue peptide of rat inositol trisphosphate receptor subtype 3. We now show that these antibodies cross-react with rat, but not human, insulin. Accordingly, the anti-inositol trisphosphate receptor subtype 3 (AB3) antibodies label electron dense cores of mature (insulin-rich) granules of rat pancreatic beta cells, and rat granule labeling was blocked by preabsorption of the AB3 antibodies with rat insulin. The immunostaining of immature, Golgi-associated proinsulin-rich granules with AB3 antibodies was very weak, indicating that cross-reactivity is limited to the hormone and not its precursor. Also, the AB3 antibodies labeled pure rat insulin crystals grown in vitro but failed to stain crystals grown from pure human insulin. By immunoprecipitation, the antibodies similarly displayed a higher affinity for rat than for human insulin. We could not confirm the labeling of somatostatin granules using AB3 antibodies.

Association of a transglutaminase-related antigen with intermediate filaments.

A mouse monoclonal antibody, G92.1.2, raised against guinea pig liver transglutaminase (TGase) recognizes an antigen present in primary mouse dermal fibroblasts. A filamentous pattern, bearing remarkable similarity to the vimentin intermediate filament (IF) network, is seen when these cells are fixed and processed for indirect immunofluorescence with the antibody. Double-label immunofluorescence reveals that the antigen reacting with the antibody colocalizes precisely with vimentin IF and that this colocalization is retained after the treatment of fibroblasts with colchicine, which induces a redistribution of the majority of IFs into perinuclear aggregates. These morphological observations are further supported by the finding that the protein reacting with G92.1.2 is retained in IF-enriched cytoskeletal preparations made by using nonionic detergent-containing high ionic strength solutions. Western blots of the IF fraction show that G92.1.2 recognizes a major band of approximately 280 kDa and does not cross react with vimentin. Furthermore, when the antibody is microinjected into live dermal fibroblasts, it causes a collapse of the vimentin IF network in the majority of injected cells. The results suggest that a form of TGase, or a TGase-related antigen, is closely associated with the vimentin IF network of primary cultures of mouse dermal fibroblasts.

Immunolocalization of the mercurial-insensitive water channel and glycerol intrinsic protein in epithelial cell plasma membranes.

Two water channel homologs were cloned recently from rat kidney, mercurial-insensitive water channel (MIWC) and glycerol intrinsic protein (GLIP). Polyclonal antibodies were raised against synthetic C-terminal peptides and purified by affinity chromatography. MIWC and GLIP antibodies recognized proteins in rat kidney with an apparent molecular mass of 30 and 27 kDa, respectively, and did not cross-react. By immunofluorescence, MIWC and GLIP were expressed together on the basolateral plasma membrane of collecting duct principal cells in kidney. By immunohistochemistry, MIWC and GLIP were expressed on tracheal epithelial cells with greater expression of GLIP on the basal plasma membrane and MIWC on the lateral membrane; only MIWC was expressed in bronchial epithelia. In eye, GLIP was expressed in conjunctival epithelium, whereas MIWC was found in iris, ciliary body, and neural cell layers in retina. MIWC and GLIP colocalized on the basolateral membrane of villus epithelial cells in colon and brain ependymal cells. Expression of MIWC and GLIP was not detected in small intestine, liver, spleen, endothelia, and cells that express water channels CHIP28 or WCH-CD. These studies suggest water/solute transporting roles for MIWC and GLIP in the urinary concentrating mechanism, cerebrospinal fluid absorption, ocular fluid balance, fecal dehydration, and airway humidification. The unexpected membrane colocalization of MIWC and GLIP in several tissues suggests an interaction at the molecular and/or functional levels.

Potential of lipid core peptide technology as a novel self-adjuvanting vaccine delivery system for multiple different synthetic peptide immunogens

This study demonstrates the effectiveness of a novel self-adjuvanting vaccine delivery system for multiple different synthetic peptide immunogens by use of lipid core peptide (LCP) technology. An LCP formulation incorporating two different protective epitopes of the surface antiphagocytic M protein of group A streptococci (GAS)-the causative agents of rheumatic fever and subsequent rheumatic heart disease-was tested in a murine parenteral immunization and GAS challenge model. Mice were immunized with the LCP-GAS formulation, which contains an M protein amino-terminal type-specific peptide sequence (8830) in combination with a conserved non-host-cross-reactive carboxy-terminal C-region peptide sequence (J8) of the M protein. Our data demonstrated immunogenicity of the LCP-8830-J8 formulation in B10.BR mice when coadministered in complete Freund's adjuvant and in the absence of a conventional adjuvant. In both cases, immunization led to induction of high-titer GAS peptide-specific serum immunoglobulin G antibody responses and induction of highly opsonic antibodies that did not cross-react with human heart tissue proteins. Moreover, mice were completely protected from GAS infection when immunized with LCP-8830-J8 in the presence or absence of a conventional adjuvant. Mice were not protected, however, following immunization with an LCP formulation containing a control peptide from a Schistosoma sp. These data support the potential of LCP technology in the development of novel self-adjuvanting multi-antigen component vaccines and point to the potential application of this system in the development of human vaccines against infectious diseases.