Characterization of a monoclonal antibody to bovine xanthine oxidase

Role of reactive oxygen metabolites in murine peritoneal macrophage phagocytosis and phagocytic killing

This study was designed to quantify the role of reactive oxygen metabolites (ROMs) in two distinct components of murine peritoneal macrophage activity, phagocytosis and killing, and to discriminate quantitatively the degree to which each component is dependent on NADPH oxidase and/or xanthine oxidase. A fluorochromatic vital staining technique was modified to simultaneously quantify phagocytosis and microbicidal activity of macrophages incubated with Candida parapsilosis targets. To determine the role of ROMs, macrophages were preincubated with free radical scavengers [superoxide dismutase (SOD) and/or catalase] or with selective inhibitors of xanthine oxidase (XO, e.g., allopurinol) or NADPH oxidase [diphenyleneiodonium (DPI)]. Phagocytosis was not affected by treatment of macrophages with SOD, catalase, allopurinol, or DPI. Candidacidal activity, however, was inhibited by SOD, allopurinol, or DPI. The inhibitory effects of DPI and allopurinol were additive. Histochemical and biochemical assays demonstrated substantial quantities of XO in murine peritoneal macrophages. The findings suggest that the generation of ROMs by XO- and NADPH oxidase-dependent pathways are each important for phagocytic killing by murine peritoneal macrophages.

Production and characterization of monoclonal antibodies directed against bovine milk fat globule membrane (MFGM)

Nine hybridomas secreting monoclonal antibodies (mAbs) to bovine milk fat globule membrane (MFGM) were produced from spleen cells of three immunized BALB/c mice. Several MFGM antigens recognized by some mAbs were identified as a 120 kDa protein and 67 kDa (butyrophilin), 57 kDa (PAS-6), 53 kDa (PAS-7), 33 kDa glycoproteins. The other mAbs secreted by four independent hybridoma clones recognized many broad bands ranging from 20 to 200 kDa. The 120 kDa protein and 67 kDa, 57 kDa, 53 kDa glycoproteins were detected by each mAb in the plasma membrane fraction prepared from a lactating bovine mammary gland. Moreover, mammary gland epithelium of a thin section was specifically stained with these mAbs, indicating that these mAbs directed against MFGM recognized membrane proteins and glycoproteins of lactating mammary epithelial cells. Upon heating of the MFGM in phosphate buffer, pH 7.4 at 100 degrees C for 10 min, the antigens still retained most of its reactivity to these mAbs, whereas, proteolytic cleavage by trypsin and chymotrypsin strongly reduced its reactivity to these mAbs by 60% or more except for two mAbs which recognized the 57 and 53 kDa glycoproteins, respectively.

Immunohistochemical localization of xanthine oxidase in human cardiac and skeletal muscle

The generation of a monoclonal antibody specific to xanthine oxidase and its use in the distribution of the enzyme in human tissue is described. Xanthine oxidase was purified from human and bovine milk by a rapid method, allowing for minimal proteolytic degradation, and the purified enzyme preparations were used for the immunization of BALB/c mice as well as for the subsequent selection of hybridomas. The hybridoma clone X1-7, IgG (2a, kappa-light chain) was selected for further analysis and demonstrated to precipitate xanthine oxidase from human liver and skeletal muscle extracts. As determined by SDS-polyacrylamide gel electrophoresis of eluates from affinity chromatography, the X1-7 antibody bound to a main protein of 155 kDa, from human milk and skeletal muscle, and to proteins of 155, 143 and 95 kDa from human liver. Immunohistochemical studies, using two of the monoclonal antibodies with differing epitope specificity, revealed xanthine oxidase to be localized mainly in the vascular smooth muscle cells but also in a proportion of endothelial cells of capillaries and smaller vessels in both human cardiac and skeletal muscle. Immunoreactivity was additionally observed in human macrophages and mast cells. The results of the present study confirm previous reports of the presence of xanthine oxidase in capillary endothelial cells, but also demonstrates additional localization of the enzyme in vascular smooth muscle cells, macrophages and mast cells. The current findings verify that the distribution of xanthine oxidase in human tissue includes cardiac and skeletal muscle.

Immunohistochemical detection of advanced glycosylation end products in diabetic tissues using monoclonal antibody to pyrraline

Pyrraline is one of the major Maillard compounds resulting from the reaction of glucose with amino compounds at slightly acidic pH. For in vivo studies, monoclonal pyrraline antibodies were raised after immunization of Balb/c mice with keyhole limpet hemocyamin-caproyl pyrraline conjugate. Of 660 hybridoma clones from one donor, 260 produced an antibody to the free hapten, two of which named Pyr-A and Pyr-B also cross-reacted with L-lysyl pyrraline. Using Pyr-B antibody and an ELISA, a gradual increase in pyrraline immunoreactivity was observed in serum albumin incubated with glucose or 3-deoxyglucosone. Plasma pyrraline levels increased fourfold (P less than 0.001) in Sprague-Dawley rats upon induction of diabetes with streptozotocin and were twofold increased in randomly selected plasmas from diabetic humans. Highly specific pyrraline immunoreactivity was detected in sclerosed glomeruli from diabetic and old normal kidneys as well as in renal arteries with arteriolosclerosis and in perivascular and peritubular sclerosed extracellular matrix and basement membranes. The preferential localization of pyrraline immunoreactivity in the extracellular matrix strengthens the notion that the advanced glycosylation reaction may contribute to decreased turnover and thickening of the extracellular matrix in diabetes and aging.

Preparation of antibodies against xanthine oxidase from human milk

1. Human xanthine oxidase [XO; EC 1.2.3.2.] was isolated by a non-proteolytic method from fresh human milk. Final purification of the protein was achieved by hydroxyapatite chromatography. Most (less than 95%) of the enzyme was released in the 0.40 M phosphate fraction at pH 6.8. 2. The specific activity of this preparation was found to be 0.047 microM min-1 mg-1 with xanthine as substrate. 3. Sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis (PAGE) separated two subunits, each with a mol. wt approximately 122 kDa. 4. On non-denaturing acrylamide gels both of these subunits exhibited oxidase-like activity with xanthine as substrate in the presence of nitroblue tetrazolium and molecular oxygen. 5. Immunoconjugates of XO were prepared by the keyhole limpet hemocyanin (KLH)- and glutaraldehyde-crosslinking techniques. 6. Polyclonal antibodies to XO were raised by i.m. injection of these conjugates into female New Zealand rabbits. 7. Western blot analysis using the semi-dry technique was employed to confirm the specificity of the antibody.

Purification and characterization of a differentiation-specific sialoglycoprotein of lactating-guinea-pig mammary tissue

A large acidic glycoprotein, PAS-I, was purified from the fat-globule membrane of guinea-pig milk. Threonine and serine accounted for over 30 mol% of the amino acids, and galactose, N-acetylgalactosamine, N-acetylglucosamine, mannose and sialic acid were the principal sugars detected. On a molar basis, sialic acid accounted for over 60% of the total sugar. Removal of sialic acid by treatment with neuraminidase revealed the presence of binding sites for peanut (Arachis hypogaea) agglutinin, a lectin specific for the sugar sequence beta-D-Gal-(beta 1----3)-D-GalNac (the T antigen). The distribution of PAS-I-related epitopes, defined by five monoclonal antibodies, was determined in the mammary gland and in other guinea-pig tissues. PAS-I was maximally expressed on the apical surfaces of secretory cells in lactating mammary tissue and was either absent, or present in much lower amounts, in the glands of virgin or pregnant animals. PAS-I epitopes were not detected in liver, heart, spleen, pancreas, ovary, uterus, lung or intestine, either by immunofluorescence microscopy or by immunoblotting techniques. Several of the PAS-I-specific antibodies bound to mucins of high Mr in human fat-globule membrane, and similarities and differences between PAS-I and the human mucins are discussed. PAS-I and epitopes of this glycoprotein will be useful as indicators of differentiation in mammary cells and of markers of the apical surface of these cells during lactation.

Immunoglobulin A monoclonal antibodies protect against Sendai virus

Immunoglobulin A anti-Sendai virus HN protein monoclonal antibodies, generated via a mucosal immunization protocol, were shown to neutralize virus in vitro and, when passively administered to the mouse respiratory tract, to protect against Sendai virus in vivo. Thus, immunoglobulin A antibodies by themselves can protect against respiratory virus infection.

Protein disulphide-isomerase from human placenta and rat liver. Purification and immunological characterization with monoclonal antibodies

The purification of human placenta and rat liver protein disulphide-isomerase (PDI, EC 5.3.4.1) and the production of a panel of monoclonal antibodies against these proteins are described. The physical and enzymic properties of human PDI and rat PDI were similar; immunological characterization revealed the presence of unique, as well as shared, antigenic determinants. Although purified rat liver PDI was present as three forms differing slightly in Mr value, evidence was presented that the multiple forms represent proteolytic degradation products of a single 59,000-Mr species. Purified human PDI had an apparent Mr of 61,200. Two of the monoclonal antibodies against human PDI partially inactivated the enzyme, and one of these in indirect immunoprecipitation led to the precipitation of all glutathione:insulin transhydrogenase activity from a crude extract of human placenta. Results of immunofluorescence experiments with HT-29 human colon carcinoma cells were consistent with localization of PDI in the nuclear membrane and cell cytoplasm.

Identification of a distinct 9S form of soluble clathrin in cultured cells and tissues

We have used a monoclonal antibody (CHC5.9) to identify clathrin (Mr 180,000; 'heavy chain') in coated vesicles, triskelion structures prepared in vitro and in high-speed supernatants (HSS) of cell homogenates from a variety of tissues and species (e.g., brain and liver from rat, cow and man; Xenopus ovaries). HSS proteins were subjected to sucrose density gradient centrifugation and gel filtration, and the fractions obtained were assayed for clathrin by enzyme-linked immunosorbent assay (ELISA) and polyacrylamide gel electrophoresis (PAGE), followed by immunoblotting. The native soluble clathrin identified in such fractions was indistinguishable from triskelions produced in vitro from purified bovine brain clathrin by several criteria, e.g. by its sedimentation coefficient (9S) and elution profile on gel filtration using Sephacryl S 300. No other major forms of soluble clathrin were detected. The results indicate that cells contain a soluble pool of clathrin and that the predominant molecular form of this soluble clathrin has properties similar to those of the triskelion obtained by dissociation studies in vitro. We hypothesize that this distinct 9S form represents a major oligomeric subunit involved in assembly and disassembly of clathrin polyhedron coats in the living cell.

Production, characterization, and applications of monoclonal antibodies reactive with soybean nodule xanthine dehydrogenase

Seven monoclonal antibodies were produced against soybean nodule xanthine dehydrogenase, an enzyme involved in ureide synthesis. Specificity of the seven monoclonal antibodies for xanthine dehydrogenase was demonstrated by immunopurifying the enzyme to homogeneity from a crude nodule extract using antibodies immobilized to Sepharose 4B beads. Each monoclonal antibody was covalently bound to Sepharose 4B beads for the preparation of immunoaffinity columns for each antibody. All seven antibodies were found to be of the IgG1,K subclass. A competitive, indirect enzyme-linked immunosorbent assay demonstrated that two of the seven antibodies shared a common epitope while the remaining five antibodies defined unique determinants on the protein. Rapid, large scale purification of active xanthine dehydrogenase to homogeneity was performed by immunoaffinity chromatography. The presence of xanthine dehydrogenase activity and protein in every organ of the soybean plant was determined. Crude extracts of nodules, roots, stems, and leaves cross-reacted with all seven monoclonal antibodies in an indirect enzyme-linked immunosorbent assay. A positive correlation was observed between the degree of cross-reactivity of a given organ and the level of enzyme activity in that organ. These data demonstrate that xanthine dehydrogenase is not nodule specific. Antigenic variability of xanthine dehydrogenase present in crude extracts from nodules of soybean, wild soybean, cowpea, lima bean, pea, and lupin were detected in the indirect enzyme-linked immunosorbent assay which corresponded to six binding patterns for xanthine dehydrogenase from these plant species. These results correspond well with the epitope determination data which showed that the seven antibodies bind to six different binding determinants on the enzyme.

Purification and tissue-specific expression of casein kinase from the lactating guinea-pig mammary gland

A serine-specific casein kinase, an integral membrane protein of the lactating guinea-pig mammary gland, has been purified from a Golgi-enriched membrane fraction, using a combination of sucrose gradient centrifugation and chromatography on ATP-agarose. The enzyme comprises a polypeptide of estimated Mr 74 000 as judged by sodium dodecyl sulphate/polyacrylamide gel electrophoresis, compared with a monomer Mr of 50 000 as determined by sucrose gradient centrifugation in the presence of 500 mM NaCl and 0.1% Triton X-100. Kinetic studies show that the purified enzyme exhibits kinetic constants distinctly different from the rabbit reticulocyte casein kinases I and II, whilst polyclonal antisera raised against the mammary gland enzyme did not cross-react with soluble liver or reticulocyte protein kinase activities. Immunoblotting and immunocytochemical analyses demonstrate the mammary gland enzyme's apparently unique location in lactating mammary gland tissue. Comparative studies with polyclonal antisera raised against bovine galactosyltransferase, show that casein kinase and galactosyltransferase have a similar intracellular localisation in the lactating mammary gland as judged by immunocytochemistry at the light level, but that casein kinase was unique to mammary gland whereas galactosyltransferase could be found in other tissues. The results extended our earlier observations which suggest a Golgi location for casein kinase, and demonstrate that future studies using this enzyme may well prove advantageous for the study of intracellular mechanisms involved in the biogenesis of organelles, in this instance the Golgi apparatus.

The intermediate filament cytoskeleton of malignant mesotheliomas and its diagnostic significance

The intermediate filament cytoskeleton of epithelial, biphasic, and fibrous malignant pleural mesotheliomas was studied by immunohistochemistry and gel electrophoresis. The results were compared with data similarly obtained from lung adenocarcinomas. All mesotheliomas immunostained with various monoclonal and polyclonal antibodies against cytokeratins. By double immunofluorescence microscopy, coexpression of cytokeratins and vimentin was found in the fusiform cells of biphasic and fibrous mesotheliomas. As determined by two-dimensional gel electrophoresis, lung adenocarcinomas exclusively expressed Cytokeratins 7, 8, 18, and 19, and the same polypeptides were found in the fibrous mesotheliomas. These four cytokeratins were also found in the epithelial and biphasic mesotheliomas, most of which, however, also expressed, additional cytokeratins, such as the basic Polypeptide 5 and, in some cases, Cytokeratins 4, 6, 14, and 17. The results demonstrate the epithelial nature of all types of malignant mesotheliomas and thus justify their classification as carcinomas. When epithelial morphology is evident, the pattern of cytokeratin expression is usually more complex, as indicated by the synthesis, in addition to the "simple epithelial" pattern (7, 8, 18, and 19), of certain cytokeratin polypeptides which hitherto have been presumed to be typical of stratified epithelia. This cytokeratin complexity and the coexpression of vimentin and cytokeratins in certain forms of mesotheliomas indicate that these tumors are a clearly distinct and complex group of carcinomas. Their special cytoskeletal filament protein expression should prove useful in differentiating mesotheliomas from other carcinomas, particularly from adenocarcinomas growing in the lung.

Specific antibodies to PAS IV, a glycoprotein of bovine milk-fat-globule membrane, bind to a similar protein in cardiac endothelial cells and epithelial cells of lung bronchioles

We recently described the tissue distribution of PAS IV (periodic acid/Schiff-positive Band IV), a hydrophobic glycoprotein isolated from bovine milk-fat-globule membrane [Greenwalt & Mather (1985) J. Cell Biol. 100, 397-408]. By using immunofluorescence techniques, PAS IV was detected in mammary epithelial cells, the bronchiolar epithelium of lung, and the capillary endothelium of several tissues, including heart, salivary gland, pancreas, spleen and intestine. In the present paper we describe the specificity of the antibodies used for these studies. Two monoclonal antibodies, E-1 and E-3, were shown by solid-phase immunoassay and immunoaffinity chromatography to be specific for PAS IV (of Mr 76000) in milk-fat-globule membrane and recognize a glycoprotein of slightly higher Mr (85000) in heart. Affinity-purified rabbit antibodies to PAS IV were also shown to recognize components of Mr 76000 and 85000 in fat-globule membrane and heart respectively, by using immunoblotting procedures after sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. Additionally, an immunoreactive protein in lung of Mr 85000 was detected. Despite these differences in molecular size, the fat-globule membrane and heart forms of PAS IV were shown to be very similar by peptide-mapping techniques. The possible significance of the expression of similar forms of PAS IV in both epithelial and capillary endothelial cells is briefly discussed.

Monoclonal antibodies prepared against PAS-I butyrophilin and GP-55 from guinea-pig milk-fat-globule membrane bind specifically to the apical pole of secretory-epithelial cells in lactating mammary tissue

Monoclonal antibodies to the three major glycoproteins of guinea-pig milk-fat-globule membrane were isolated. The specificity of these antibodies was determined by solid-phase immunoassays and by immunoblotting and autoradiographic techniques after one- and two-dimensional gel electrophoresis. The antibodies bound to PAS-I, a sialoglycoprotein of Mr greater than or equal to 200 000 and the glycoproteins butyrophilin and GP-55, of Mr 63 000 and 55 000, respectively. Immunolocalization studies showed that all three proteins were highly concentrated in the apical pole of secretory-epithelial cells in mammary tissue during lactation. PAS-I, butyrophilin or GP-55, were not detected in either the basal cytoplasm of mammary epithelial cells or in myoepithelial cells, capillary endothelial cells or other cells found in the mammary gland. These proteins were either present in small amounts or were absent from mammary tissue taken in late pregnancy. The monoclonal antibodies characterized in this study will therefore be useful as probes for studies of the biogenesis of apical membrane proteins in mammary epithelial cells during lactation.